diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 28e429c234a3..b2f5062cf967 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -34,7 +34,6 @@ ChromeUtils.defineESModuleGetters(this, {
   LoginHelper: "resource://gre/modules/LoginHelper.sys.mjs",
   LoginManagerParent: "resource://gre/modules/LoginManagerParent.sys.mjs",
   MigrationUtils: "resource:///modules/MigrationUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   NewTabUtils: "resource://gre/modules/NewTabUtils.sys.mjs",
   NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
   PageThumbs: "resource://gre/modules/PageThumbs.sys.mjs",
@@ -91,6 +90,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   CustomizableUI: "resource:///modules/CustomizableUI.jsm",
   ExtensionsUI: "resource:///modules/ExtensionsUI.jsm",
   HomePage: "resource:///modules/HomePage.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   OpenInTabsUtils: "resource:///modules/OpenInTabsUtils.jsm",
   PageActions: "resource:///modules/PageActions.jsm",
   ProcessHangMonitor: "resource:///modules/ProcessHangMonitor.jsm",
diff --git a/browser/base/content/test/performance/PerfTestHelpers.sys.mjs b/browser/base/content/test/performance/PerfTestHelpers.sys.mjs
index caa832c2e581..075e436331c6 100644
--- a/browser/base/content/test/performance/PerfTestHelpers.sys.mjs
+++ b/browser/base/content/test/performance/PerfTestHelpers.sys.mjs
@@ -3,9 +3,11 @@
 
 const lazy = {};
 
-ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
-});
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 export var PerfTestHelpers = {
   /**
diff --git a/browser/components/BrowserGlue.sys.mjs b/browser/components/BrowserGlue.sys.mjs
index db8c60ccf0ee..2115081c0aba 100644
--- a/browser/components/BrowserGlue.sys.mjs
+++ b/browser/components/BrowserGlue.sys.mjs
@@ -32,7 +32,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
   Interactions: "resource:///modules/Interactions.sys.mjs",
   Log: "resource://gre/modules/Log.sys.mjs",
   LoginBreaches: "resource:///modules/LoginBreaches.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   NewTabUtils: "resource://gre/modules/NewTabUtils.sys.mjs",
   NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
   Normandy: "resource://normandy/Normandy.sys.mjs",
@@ -89,6 +88,7 @@ XPCOMUtils.defineLazyModuleGetters(lazy, {
   Discovery: "resource:///modules/Discovery.jsm",
   ExtensionsUI: "resource:///modules/ExtensionsUI.jsm",
   HomePage: "resource:///modules/HomePage.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   OnboardingMessageProvider:
     "resource://activity-stream/lib/OnboardingMessageProvider.jsm",
   PageActions: "resource:///modules/PageActions.jsm",
diff --git a/browser/components/doh/test/unit/head.js b/browser/components/doh/test/unit/head.js
index 5c64c867598d..eb19dac8a1f1 100644
--- a/browser/components/doh/test/unit/head.js
+++ b/browser/components/doh/test/unit/head.js
@@ -4,9 +4,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { PromiseUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/PromiseUtils.sys.mjs"
 );
diff --git a/browser/components/downloads/DownloadsCommon.sys.mjs b/browser/components/downloads/DownloadsCommon.sys.mjs
index 951e7e8cd9e7..61551c231d95 100644
--- a/browser/components/downloads/DownloadsCommon.sys.mjs
+++ b/browser/components/downloads/DownloadsCommon.sys.mjs
@@ -34,12 +34,12 @@ ChromeUtils.defineESModuleGetters(lazy, {
   DownloadHistory: "resource://gre/modules/DownloadHistory.sys.mjs",
   DownloadUtils: "resource://gre/modules/DownloadUtils.sys.mjs",
   Downloads: "resource://gre/modules/Downloads.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
 });
 
 XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   BrowserWindowTracker: "resource:///modules/BrowserWindowTracker.jsm",
 });
 
diff --git a/browser/components/downloads/content/allDownloadsView.js b/browser/components/downloads/content/allDownloadsView.js
index 451250c64f8f..9245127b0e05 100644
--- a/browser/components/downloads/content/allDownloadsView.js
+++ b/browser/components/downloads/content/allDownloadsView.js
@@ -12,12 +12,12 @@ ChromeUtils.defineESModuleGetters(this, {
   DownloadsCommon: "resource:///modules/DownloadsCommon.sys.mjs",
   DownloadsViewUI: "resource:///modules/DownloadsViewUI.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
 });
 
 XPCOMUtils.defineLazyModuleGetters(this, {
   BrowserWindowTracker: "resource:///modules/BrowserWindowTracker.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 /**
diff --git a/browser/components/downloads/content/downloads.js b/browser/components/downloads/content/downloads.js
index d3e3ac789756..7cb4a5042cc2 100644
--- a/browser/components/downloads/content/downloads.js
+++ b/browser/components/downloads/content/downloads.js
@@ -38,9 +38,13 @@ var { XPCOMUtils } = ChromeUtils.importESModule(
 ChromeUtils.defineESModuleGetters(this, {
   DownloadsViewUI: "resource:///modules/DownloadsViewUI.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  this,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 const { Integration } = ChromeUtils.importESModule(
   "resource://gre/modules/Integration.sys.mjs"
diff --git a/browser/components/downloads/test/unit/head.js b/browser/components/downloads/test/unit/head.js
index b0774a45e213..2f0326e77937 100644
--- a/browser/components/downloads/test/unit/head.js
+++ b/browser/components/downloads/test/unit/head.js
@@ -3,9 +3,13 @@ ChromeUtils.defineESModuleGetters(this, {
   DownloadsCommon: "resource:///modules/DownloadsCommon.sys.mjs",
   FileTestUtils: "resource://testing-common/FileTestUtils.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   TestUtils: "resource://testing-common/TestUtils.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  this,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 async function createDownloadedFile(pathname, contents) {
   info("createDownloadedFile: " + pathname);
diff --git a/browser/components/extensions/test/xpcshell/head.js b/browser/components/extensions/test/xpcshell/head.js
index 1ae29fb8a0a4..1d5045d3252f 100644
--- a/browser/components/extensions/test/xpcshell/head.js
+++ b/browser/components/extensions/test/xpcshell/head.js
@@ -12,7 +12,6 @@ const { AppConstants } = ChromeUtils.importESModule(
 // eslint-disable-next-line no-unused-vars
 ChromeUtils.defineESModuleGetters(this, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   TestUtils: "resource://testing-common/TestUtils.sys.mjs",
 });
 
@@ -21,6 +20,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   ExtensionData: "resource://gre/modules/Extension.jsm",
   ExtensionTestUtils: "resource://testing-common/ExtensionXPCShellUtils.jsm",
   HttpServer: "resource://testing-common/httpd.js",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   Schemas: "resource://gre/modules/Schemas.jsm",
 });
 
diff --git a/browser/components/migration/ChromeProfileMigrator.sys.mjs b/browser/components/migration/ChromeProfileMigrator.sys.mjs
index dabff01cb996..c2455db17122 100644
--- a/browser/components/migration/ChromeProfileMigrator.sys.mjs
+++ b/browser/components/migration/ChromeProfileMigrator.sys.mjs
@@ -10,6 +10,7 @@ const AUTH_TYPE = {
   SCHEME_DIGEST: 2,
 };
 
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 import { MigrationUtils } from "resource:///modules/MigrationUtils.sys.mjs";
 import { MigratorBase } from "resource:///modules/MigratorBase.sys.mjs";
@@ -19,11 +20,14 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   ChromeMigrationUtils: "resource:///modules/ChromeMigrationUtils.sys.mjs",
   FormHistory: "resource://gre/modules/FormHistory.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
   Qihoo360seMigrationUtils: "resource:///modules/360seMigrationUtils.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 /**
  * Converts an array of chrome bookmark objects into one our own places code
  * understands.
diff --git a/browser/components/migration/tests/unit/head_migration.js b/browser/components/migration/tests/unit/head_migration.js
index 6c09f99b4353..7537bb0baf05 100644
--- a/browser/components/migration/tests/unit/head_migration.js
+++ b/browser/components/migration/tests/unit/head_migration.js
@@ -6,9 +6,7 @@ var { MigrationUtils } = ChromeUtils.importESModule(
 var { LoginHelper } = ChromeUtils.importESModule(
   "resource://gre/modules/LoginHelper.sys.mjs"
 );
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { PlacesUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/PlacesUtils.sys.mjs"
 );
diff --git a/browser/components/search/test/unit/test_urlTelemetry.js b/browser/components/search/test/unit/test_urlTelemetry.js
index abd5a19d66d7..bd46f39e5bc8 100644
--- a/browser/components/search/test/unit/test_urlTelemetry.js
+++ b/browser/components/search/test/unit/test_urlTelemetry.js
@@ -1,15 +1,22 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
 ChromeUtils.defineESModuleGetters(this, {
   BrowserSearchTelemetry: "resource:///modules/BrowserSearchTelemetry.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   SearchSERPTelemetry: "resource:///modules/SearchSERPTelemetry.sys.mjs",
   SearchUtils: "resource://gre/modules/SearchUtils.sys.mjs",
   TelemetryTestUtils: "resource://testing-common/TelemetryTestUtils.sys.mjs",
   sinon: "resource://testing-common/Sinon.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(this, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 const TESTS = [
   {
     title: "Google search access point",
diff --git a/browser/components/search/test/unit/test_urlTelemetry_generic.js b/browser/components/search/test/unit/test_urlTelemetry_generic.js
index 09ee79ab9fd2..9ef613daaf98 100644
--- a/browser/components/search/test/unit/test_urlTelemetry_generic.js
+++ b/browser/components/search/test/unit/test_urlTelemetry_generic.js
@@ -1,9 +1,12 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+
 ChromeUtils.defineESModuleGetters(this, {
   BrowserSearchTelemetry: "resource:///modules/BrowserSearchTelemetry.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   SearchSERPTelemetry: "resource:///modules/SearchSERPTelemetry.sys.mjs",
   SearchSERPTelemetryUtils: "resource:///modules/SearchSERPTelemetry.sys.mjs",
   SearchUtils: "resource://gre/modules/SearchUtils.sys.mjs",
@@ -11,6 +14,10 @@ ChromeUtils.defineESModuleGetters(this, {
   sinon: "resource://testing-common/Sinon.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(this, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 const TEST_PROVIDER_INFO = [
   {
     telemetryId: "example",
diff --git a/browser/components/sessionstore/test/coopHeaderCommon.sjs b/browser/components/sessionstore/test/coopHeaderCommon.sjs
index 856ed14b45de..5c4801718cef 100644
--- a/browser/components/sessionstore/test/coopHeaderCommon.sjs
+++ b/browser/components/sessionstore/test/coopHeaderCommon.sjs
@@ -1,8 +1,6 @@
 function handleRequest(request, response) {
   Cu.importGlobalProperties(["URLSearchParams"]);
-  let { NetUtil } = ChromeUtils.importESModule(
-    "resource://gre/modules/NetUtil.sys.mjs"
-  );
+  let { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
   let query = new URLSearchParams(request.queryString);
 
   response.setHeader("Cross-Origin-Opener-Policy", "same-origin", false);
diff --git a/browser/modules/WindowsPreviewPerTab.jsm b/browser/modules/WindowsPreviewPerTab.jsm
index 446634853427..dc5f4fddba52 100644
--- a/browser/modules/WindowsPreviewPerTab.jsm
+++ b/browser/modules/WindowsPreviewPerTab.jsm
@@ -43,9 +43,7 @@
  */
 var EXPORTED_SYMBOLS = ["AeroPeek"];
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { PlacesUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/PlacesUtils.sys.mjs"
 );
diff --git a/browser/tools/mozscreenshots/mozscreenshots/extension/configurations/ControlCenter.sys.mjs b/browser/tools/mozscreenshots/mozscreenshots/extension/configurations/ControlCenter.sys.mjs
index f630fd064bf8..2ada0e831c42 100644
--- a/browser/tools/mozscreenshots/mozscreenshots/extension/configurations/ControlCenter.sys.mjs
+++ b/browser/tools/mozscreenshots/mozscreenshots/extension/configurations/ControlCenter.sys.mjs
@@ -9,7 +9,7 @@ import { UrlClassifierTestUtils } from "resource://testing-common/UrlClassifierT
 
 import { SitePermissions } from "resource:///modules/SitePermissions.sys.mjs";
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const CC_SELECTORS = ["#identity-popup", "#urlbar-input-container"];
 const PP_SELECTORS = ["#protections-popup", "#urlbar-input-container"];
diff --git a/chrome/test/unit/test_create_channel_chrome_url.js b/chrome/test/unit/test_create_channel_chrome_url.js
index 2d1c727b3b6f..19c154cba81c 100644
--- a/chrome/test/unit/test_create_channel_chrome_url.js
+++ b/chrome/test/unit/test_create_channel_chrome_url.js
@@ -4,9 +4,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function testURL(url) {
   Services.io.newChannelFromURI(
diff --git a/devtools/client/shared/remote-debugging/adb/adb-binary.js b/devtools/client/shared/remote-debugging/adb/adb-binary.js
index 447bb5661166..0822b9b43b80 100644
--- a/devtools/client/shared/remote-debugging/adb/adb-binary.js
+++ b/devtools/client/shared/remote-debugging/adb/adb-binary.js
@@ -15,8 +15,12 @@ ChromeUtils.defineModuleGetter(
 );
 ChromeUtils.defineESModuleGetters(lazy, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 loader.lazyGetter(this, "UNPACKED_ROOT_PATH", () => {
   return PathUtils.join(PathUtils.localProfileDir, "adb");
 });
diff --git a/devtools/client/shared/remote-debugging/adb/xpcshell/test_adb.js b/devtools/client/shared/remote-debugging/adb/xpcshell/test_adb.js
index c546712fae9e..a140d805a1d8 100644
--- a/devtools/client/shared/remote-debugging/adb/xpcshell/test_adb.js
+++ b/devtools/client/shared/remote-debugging/adb/xpcshell/test_adb.js
@@ -6,9 +6,7 @@
 const { ExtensionTestUtils } = ChromeUtils.import(
   "resource://testing-common/ExtensionXPCShellUtils.jsm"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const {
   getFileForBinary,
 } = require("resource://devtools/client/shared/remote-debugging/adb/adb-binary.js");
diff --git a/devtools/client/styleeditor/StyleEditorUI.sys.mjs b/devtools/client/styleeditor/StyleEditorUI.sys.mjs
index 9cca1e86fc25..dc9b8ab3b5e6 100644
--- a/devtools/client/styleeditor/StyleEditorUI.sys.mjs
+++ b/devtools/client/styleeditor/StyleEditorUI.sys.mjs
@@ -40,8 +40,12 @@ loader.lazyRequireGetter(
 
 ChromeUtils.defineESModuleGetters(lazy, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 loader.lazyRequireGetter(
   lazy,
   "ResponsiveUIManager",
diff --git a/devtools/client/styleeditor/StyleSheetEditor.sys.mjs b/devtools/client/styleeditor/StyleSheetEditor.sys.mjs
index c2b981e20439..c863b5b2671b 100644
--- a/devtools/client/styleeditor/StyleSheetEditor.sys.mjs
+++ b/devtools/client/styleeditor/StyleSheetEditor.sys.mjs
@@ -27,8 +27,12 @@ loader.lazyGetter(lazy, "BufferStream", () => {
 
 ChromeUtils.defineESModuleGetters(lazy, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 import {
   getString,
diff --git a/devtools/server/actors/network-monitor/network-content.js b/devtools/server/actors/network-monitor/network-content.js
index 8dd339041e00..c292d9da0500 100644
--- a/devtools/server/actors/network-monitor/network-content.js
+++ b/devtools/server/actors/network-monitor/network-content.js
@@ -10,9 +10,13 @@ const {
 } = require("resource://devtools/shared/specs/network-content.js");
 
 const lazy = {};
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   NetworkUtils:
     "resource://devtools/shared/network-observer/NetworkUtils.sys.mjs",
 });
diff --git a/devtools/server/tests/xpcshell/head_dbg.js b/devtools/server/tests/xpcshell/head_dbg.js
index 88499cc05834..84497b011bf1 100644
--- a/devtools/server/tests/xpcshell/head_dbg.js
+++ b/devtools/server/tests/xpcshell/head_dbg.js
@@ -26,9 +26,7 @@ const { worker } = ChromeUtils.import(
   "resource://devtools/shared/loader/worker-loader.js"
 );
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Always log packets when running tests. runxpcshelltests.py will throw
 // the output away anyway, unless you give it the --verbose flag.
diff --git a/devtools/shared/DevToolsUtils.js b/devtools/shared/DevToolsUtils.js
index 07db2ac46f15..63bbb87c43c4 100644
--- a/devtools/shared/DevToolsUtils.js
+++ b/devtools/shared/DevToolsUtils.js
@@ -523,8 +523,7 @@ Object.defineProperty(exports, "assert", {
 });
 
 DevToolsUtils.defineLazyGetter(this, "NetUtil", () => {
-  return ChromeUtils.importESModule("resource://gre/modules/NetUtil.sys.mjs")
-    .NetUtil;
+  return ChromeUtils.import("resource://gre/modules/NetUtil.jsm").NetUtil;
 });
 
 /**
diff --git a/devtools/shared/commands/resource/tests/browser_resources_network_events_parent_process.js b/devtools/shared/commands/resource/tests/browser_resources_network_events_parent_process.js
index c5b3e436db0f..adf1e1ec52e8 100644
--- a/devtools/shared/commands/resource/tests/browser_resources_network_events_parent_process.js
+++ b/devtools/shared/commands/resource/tests/browser_resources_network_events_parent_process.js
@@ -166,8 +166,8 @@ add_task(async function testParentProcessRequests() {
     tab.linkedBrowser,
     [requestUrl],
     async function (uri) {
-      const { NetUtil } = ChromeUtils.importESModule(
-        "resource://gre/modules/NetUtil.sys.mjs"
+      const { NetUtil } = ChromeUtils.import(
+        "resource://gre/modules/NetUtil.jsm"
       );
       const channel = NetUtil.newChannel({
         uri,
@@ -198,8 +198,8 @@ add_task(async function testParentProcessRequests() {
     secondTab.linkedBrowser,
     [requestUrl],
     async function (uri) {
-      const { NetUtil } = ChromeUtils.importESModule(
-        "resource://gre/modules/NetUtil.sys.mjs"
+      const { NetUtil } = ChromeUtils.import(
+        "resource://gre/modules/NetUtil.jsm"
       );
       const channel = NetUtil.newChannel({
         uri,
diff --git a/devtools/shared/layout/utils.js b/devtools/shared/layout/utils.js
index 804290654a2c..3e690fc5c36c 100644
--- a/devtools/shared/layout/utils.js
+++ b/devtools/shared/layout/utils.js
@@ -10,9 +10,11 @@ loader.lazyRequireGetter(
   "resource://devtools/shared/DevToolsUtils.js"
 );
 const lazy = {};
-ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
-});
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 const SHEET_TYPE = {
   agent: "AGENT_SHEET",
diff --git a/devtools/shared/loader/base-loader.sys.mjs b/devtools/shared/loader/base-loader.sys.mjs
index b9d625f3e302..78998d9b7756 100644
--- a/devtools/shared/loader/base-loader.sys.mjs
+++ b/devtools/shared/loader/base-loader.sys.mjs
@@ -20,9 +20,11 @@ XPCOMUtils.defineLazyServiceGetter(
   "nsIResProtocolHandler"
 );
 
-ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
-});
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 // Define some shortcuts.
 function* getOwnIdentifiers(x) {
diff --git a/devtools/shared/loader/loader-plugin-raw.sys.mjs b/devtools/shared/loader/loader-plugin-raw.sys.mjs
index 1e645ad3beef..a7aa630ce5db 100644
--- a/devtools/shared/loader/loader-plugin-raw.sys.mjs
+++ b/devtools/shared/loader/loader-plugin-raw.sys.mjs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 /**
  * A function that can be used as part of a require hook for a
diff --git a/devtools/shared/network-observer/NetworkHelper.sys.mjs b/devtools/shared/network-observer/NetworkHelper.sys.mjs
index 3014930faf7a..3523c0854ef9 100644
--- a/devtools/shared/network-observer/NetworkHelper.sys.mjs
+++ b/devtools/shared/network-observer/NetworkHelper.sys.mjs
@@ -67,8 +67,10 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   DevToolsInfaillibleUtils:
     "resource://devtools/shared/DevToolsInfaillibleUtils.sys.mjs",
+});
 
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 // It would make sense to put this in the above
diff --git a/devtools/shared/network-observer/NetworkOverride.sys.mjs b/devtools/shared/network-observer/NetworkOverride.sys.mjs
index 1b9ef6c873fe..a7857bcd76c0 100644
--- a/devtools/shared/network-observer/NetworkOverride.sys.mjs
+++ b/devtools/shared/network-observer/NetworkOverride.sys.mjs
@@ -8,7 +8,7 @@
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const lazy = {};
 
diff --git a/devtools/shared/network-observer/NetworkResponseListener.sys.mjs b/devtools/shared/network-observer/NetworkResponseListener.sys.mjs
index 2735882f22c5..23246c73de79 100644
--- a/devtools/shared/network-observer/NetworkResponseListener.sys.mjs
+++ b/devtools/shared/network-observer/NetworkResponseListener.sys.mjs
@@ -2,16 +2,21 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
 const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
+  getResponseCacheObject:
+    "resource://devtools/shared/platform/CacheEntry.sys.mjs",
   NetworkHelper:
     "resource://devtools/shared/network-observer/NetworkHelper.sys.mjs",
   NetworkUtils:
     "resource://devtools/shared/network-observer/NetworkUtils.sys.mjs",
-  getResponseCacheObject:
-    "resource://devtools/shared/platform/CacheEntry.sys.mjs",
+});
+
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 // Network logging
diff --git a/devtools/shared/transport/tests/xpcshell/head_dbg.js b/devtools/shared/transport/tests/xpcshell/head_dbg.js
index 18e235f17e20..42794c771286 100644
--- a/devtools/shared/transport/tests/xpcshell/head_dbg.js
+++ b/devtools/shared/transport/tests/xpcshell/head_dbg.js
@@ -12,9 +12,7 @@ var CC = Components.Constructor;
 const { require } = ChromeUtils.importESModule(
   "resource://devtools/shared/loader/Loader.sys.mjs"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // We do not want to log packets by default, because in some tests,
 // we can be sending large amounts of data. The test harness has
diff --git a/docshell/test/unit/head_docshell.js b/docshell/test/unit/head_docshell.js
index 3999e949c39a..9e2af04b6b94 100644
--- a/docshell/test/unit/head_docshell.js
+++ b/docshell/test/unit/head_docshell.js
@@ -7,7 +7,6 @@ var { XPCOMUtils } = ChromeUtils.importESModule(
 );
 
 ChromeUtils.defineESModuleGetters(this, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   SearchTestUtils: "resource://testing-common/SearchTestUtils.sys.mjs",
   SearchUtils: "resource://gre/modules/SearchUtils.sys.mjs",
   TestUtils: "resource://testing-common/TestUtils.sys.mjs",
@@ -16,6 +15,7 @@ ChromeUtils.defineESModuleGetters(this, {
 XPCOMUtils.defineLazyModuleGetters(this, {
   AddonTestUtils: "resource://testing-common/AddonTestUtils.jsm",
   HttpServer: "resource://testing-common/httpd.js",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 var profileDir = do_get_profile();
diff --git a/dom/base/test/unit/head_utilities.js b/dom/base/test/unit/head_utilities.js
index cbf0a1b2a71a..4b6d41ff1b33 100644
--- a/dom/base/test/unit/head_utilities.js
+++ b/dom/base/test/unit/head_utilities.js
@@ -30,9 +30,7 @@ var {
   HttpError,
   HttpServer,
 } = ChromeUtils.import("resource://testing-common/httpd.js");
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const nsIDocumentEncoder = Ci.nsIDocumentEncoder;
 const replacementChar =
diff --git a/dom/base/test/unit/test_xhr_document.js b/dom/base/test/unit/test_xhr_document.js
index 94b9f6416bd2..aa96c283c03c 100644
--- a/dom/base/test/unit/test_xhr_document.js
+++ b/dom/base/test/unit/test_xhr_document.js
@@ -11,9 +11,7 @@ var docbody =
   '<html xmlns="http://www.w3.org/1999/xhtml"><head></head><body></body></html>';
 
 function handler(metadata, response) {
-  var { NetUtil } = ChromeUtils.importESModule(
-    "resource://gre/modules/NetUtil.sys.mjs"
-  );
+  var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
   let body = NetUtil.readInputStreamToString(
     metadata.bodyInputStream,
diff --git a/dom/manifest/test/cookie_checker.sjs b/dom/manifest/test/cookie_checker.sjs
index 5405a6207bbe..fa5df00d44ea 100644
--- a/dom/manifest/test/cookie_checker.sjs
+++ b/dom/manifest/test/cookie_checker.sjs
@@ -1,7 +1,5 @@
 "use strict";
-let { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+let { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function handleRequest(request, response) {
   response.setStatusLine(request.httpVersion, 200);
diff --git a/dom/manifest/test/file_testserver.sjs b/dom/manifest/test/file_testserver.sjs
index 93ea9c64a8f3..bcceb1550418 100644
--- a/dom/manifest/test/file_testserver.sjs
+++ b/dom/manifest/test/file_testserver.sjs
@@ -1,7 +1,5 @@
 "use strict";
-let { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+let { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 Cu.importGlobalProperties(["URLSearchParams"]);
 
 function loadHTMLFromFile(path) {
diff --git a/dom/media/IdpSandbox.sys.mjs b/dom/media/IdpSandbox.sys.mjs
index 8b94abf7dd99..bd864b2fabc0 100644
--- a/dom/media/IdpSandbox.sys.mjs
+++ b/dom/media/IdpSandbox.sys.mjs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 /** This little class ensures that redirects maintain an https:// origin */
 function RedirectHttpsOnly() {}
diff --git a/dom/push/PushServiceHttp2.sys.mjs b/dom/push/PushServiceHttp2.sys.mjs
index 000b0f7cc238..803f19bcef1a 100644
--- a/dom/push/PushServiceHttp2.sys.mjs
+++ b/dom/push/PushServiceHttp2.sys.mjs
@@ -6,7 +6,7 @@ import { PushDB } from "resource://gre/modules/PushDB.sys.mjs";
 import { PushRecord } from "resource://gre/modules/PushRecord.sys.mjs";
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 import { clearTimeout, setTimeout } from "resource://gre/modules/Timer.sys.mjs";
 
 import { PushCrypto } from "resource://gre/modules/PushCrypto.sys.mjs";
diff --git a/dom/push/test/xpcshell/head-http2.js b/dom/push/test/xpcshell/head-http2.js
index ef9ec6169025..2538bd3caa7f 100644
--- a/dom/push/test/xpcshell/head-http2.js
+++ b/dom/push/test/xpcshell/head-http2.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Returns the test H/2 server port, throwing if it's missing or invalid.
 function getTestServerPort() {
diff --git a/dom/security/test/csp/file_bug888172.sjs b/dom/security/test/csp/file_bug888172.sjs
index dfce8612898f..adc0f7740cb1 100644
--- a/dom/security/test/csp/file_bug888172.sjs
+++ b/dom/security/test/csp/file_bug888172.sjs
@@ -1,8 +1,6 @@
 // SJS file for CSP mochitests
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function loadHTMLFromFile(path) {
   // Load the HTML to return in the response from file.
diff --git a/dom/security/test/csp/file_bug910139.sjs b/dom/security/test/csp/file_bug910139.sjs
index 7f012ba18030..56647134f80b 100644
--- a/dom/security/test/csp/file_bug910139.sjs
+++ b/dom/security/test/csp/file_bug910139.sjs
@@ -1,8 +1,6 @@
 // Server side js file for bug 910139, see file test_bug910139.html for details.
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function loadResponseFromFile(path) {
   var testHTMLFile = Components.classes["@mozilla.org/file/directory_service;1"]
diff --git a/dom/security/test/csp/file_ignore_unsafe_inline_multiple_policies_server.sjs b/dom/security/test/csp/file_ignore_unsafe_inline_multiple_policies_server.sjs
index 0473ed26b02e..c27aee0f4296 100644
--- a/dom/security/test/csp/file_ignore_unsafe_inline_multiple_policies_server.sjs
+++ b/dom/security/test/csp/file_ignore_unsafe_inline_multiple_policies_server.sjs
@@ -2,9 +2,7 @@
 // * Bug 1004703 - ignore 'unsafe-inline' if nonce- or hash-source specified
 // * Bug 1198422: should not block inline script if default-src is not specified
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function loadHTMLFromFile(path) {
   // Load the HTML to return in the response from file.
diff --git a/dom/security/test/csp/file_report_chromescript.js b/dom/security/test/csp/file_report_chromescript.js
index b957972dcd4c..56364605dca1 100644
--- a/dom/security/test/csp/file_report_chromescript.js
+++ b/dom/security/test/csp/file_report_chromescript.js
@@ -1,8 +1,6 @@
 /* eslint-env mozilla/chrome-script */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 Cu.importGlobalProperties(["TextDecoder"]);
 
diff --git a/dom/security/test/csp/file_testserver.sjs b/dom/security/test/csp/file_testserver.sjs
index fab9e000b256..0363fc2c7afb 100644
--- a/dom/security/test/csp/file_testserver.sjs
+++ b/dom/security/test/csp/file_testserver.sjs
@@ -1,8 +1,6 @@
 // SJS file for CSP mochitests
 "use strict";
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 Components.utils.importGlobalProperties(["URLSearchParams"]);
 
 function loadHTMLFromFile(path) {
diff --git a/dom/security/test/csp/file_upgrade_insecure_reporting_server.sjs b/dom/security/test/csp/file_upgrade_insecure_reporting_server.sjs
index e83b7238effc..e5ea844bba07 100644
--- a/dom/security/test/csp/file_upgrade_insecure_reporting_server.sjs
+++ b/dom/security/test/csp/file_upgrade_insecure_reporting_server.sjs
@@ -1,9 +1,7 @@
 // Custom *.sjs specifically for the needs of Bug
 // Bug 1139297 - Implement CSP upgrade-insecure-requests directive
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // small red image
 const IMG_BYTES = atob(
diff --git a/dom/security/test/mixedcontentblocker/file_server.sjs b/dom/security/test/mixedcontentblocker/file_server.sjs
index b5f270fddcb9..3270a4ce1538 100644
--- a/dom/security/test/mixedcontentblocker/file_server.sjs
+++ b/dom/security/test/mixedcontentblocker/file_server.sjs
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function ERR(response, msg) {
   dump("ERROR: " + msg + "\n");
diff --git a/dom/security/test/unit/test_csp_reports.js b/dom/security/test/unit/test_csp_reports.js
index 7248f1b4117a..5cc9f64eb897 100644
--- a/dom/security/test/unit/test_csp_reports.js
+++ b/dom/security/test/unit/test_csp_reports.js
@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
 
 var httpServer = new HttpServer();
diff --git a/dom/security/test/unit/test_csp_upgrade_insecure_request_header.js b/dom/security/test/unit/test_csp_upgrade_insecure_request_header.js
index 13400f9c36e7..715ecbc979ca 100644
--- a/dom/security/test/unit/test_csp_upgrade_insecure_request_header.js
+++ b/dom/security/test/unit/test_csp_upgrade_insecure_request_header.js
@@ -1,7 +1,5 @@
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/dom/security/test/unit/test_https_only_https_first_default_port.js b/dom/security/test/unit/test_https_only_https_first_default_port.js
index f1303f4029c4..8960fd74b00f 100644
--- a/dom/security/test/unit/test_https_only_https_first_default_port.js
+++ b/dom/security/test/unit/test_https_only_https_first_default_port.js
@@ -1,7 +1,5 @@
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const TEST_PATH = "/https_only_https_first_port";
 var httpserver = null;
diff --git a/dom/security/test/unit/test_https_only_https_first_prefs.js b/dom/security/test/unit/test_https_only_https_first_prefs.js
index 9848a4ff2668..d3ce4e861563 100644
--- a/dom/security/test/unit/test_https_only_https_first_prefs.js
+++ b/dom/security/test/unit/test_https_only_https_first_prefs.js
@@ -1,7 +1,5 @@
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/dom/security/test/unit/test_isOriginPotentiallyTrustworthy.js b/dom/security/test/unit/test_isOriginPotentiallyTrustworthy.js
index acada7e9568d..b218f1438fcd 100644
--- a/dom/security/test/unit/test_isOriginPotentiallyTrustworthy.js
+++ b/dom/security/test/unit/test_isOriginPotentiallyTrustworthy.js
@@ -6,9 +6,7 @@
  * <https://w3c.github.io/webappsec-secure-contexts/#is-origin-trustworthy>.
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 Services.prefs.setCharPref(
   "dom.securecontext.allowlist",
diff --git a/dom/webtransport/test/xpcshell/test_close.js b/dom/webtransport/test/xpcshell/test_close.js
index 53b11599eb05..5c0aa0017cf4 100644
--- a/dom/webtransport/test/xpcshell/test_close.js
+++ b/dom/webtransport/test/xpcshell/test_close.js
@@ -13,9 +13,7 @@ registerCleanupFunction(async () => {
   Services.prefs.clearUserPref("network.dns.localDomains");
 });
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function readFile(file) {
   let fstream = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
diff --git a/dom/webtransport/test/xpcshell/test_simple_conn.js b/dom/webtransport/test/xpcshell/test_simple_conn.js
index 8c0c5a3a6651..e5711c0baf41 100644
--- a/dom/webtransport/test/xpcshell/test_simple_conn.js
+++ b/dom/webtransport/test/xpcshell/test_simple_conn.js
@@ -22,9 +22,7 @@ registerCleanupFunction(async () => {
   Services.prefs.clearUserPref("network.webtransport.redirect.enabled");
 });
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function readFile(file) {
   let fstream = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
diff --git a/dom/webtransport/test/xpcshell/test_simple_stream.js b/dom/webtransport/test/xpcshell/test_simple_stream.js
index 49fad973a423..4efbfe2539be 100644
--- a/dom/webtransport/test/xpcshell/test_simple_stream.js
+++ b/dom/webtransport/test/xpcshell/test_simple_stream.js
@@ -21,9 +21,7 @@ registerCleanupFunction(async () => {
   Services.prefs.clearUserPref("network.webtransport.redirect.enabled");
 });
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function readFile(file) {
   let fstream = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
diff --git a/dom/xslt/tests/XSLTMark/XSLTMark-static.js b/dom/xslt/tests/XSLTMark/XSLTMark-static.js
index 5c1f1ba2f8df..fcca33e72bf1 100644
--- a/dom/xslt/tests/XSLTMark/XSLTMark-static.js
+++ b/dom/xslt/tests/XSLTMark/XSLTMark-static.js
@@ -12,9 +12,7 @@ const nsIFilePicker = Ci.nsIFilePicker;
 const STDURLMUT_CTRID = "@mozilla.org/network/standard-url-mutator;1";
 const nsIURIMutator = Ci.nsIURIMutator;
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 var gStop = false;
 
diff --git a/extensions/permissions/test/unit/head.js b/extensions/permissions/test/unit/head.js
index ae356ca91759..b5b2518e226c 100644
--- a/extensions/permissions/test/unit/head.js
+++ b/extensions/permissions/test/unit/head.js
@@ -2,9 +2,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Helper to step a generator function and catch a StopIteration exception.
 function do_run_generator(generator) {
diff --git a/image/test/unit/async_load_tests.js b/image/test/unit/async_load_tests.js
index 1723f70c474e..06792349eeb0 100644
--- a/image/test/unit/async_load_tests.js
+++ b/image/test/unit/async_load_tests.js
@@ -8,9 +8,7 @@
 /* import-globals-from image_load_helpers.js */
 
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const ReferrerInfo = Components.Constructor(
   "@mozilla.org/referrer-info;1",
   "nsIReferrerInfo",
diff --git a/image/test/unit/test_imgtools.js b/image/test/unit/test_imgtools.js
index 689a4ed56f4d..7f832a6b12b3 100644
--- a/image/test/unit/test_imgtools.js
+++ b/image/test/unit/test_imgtools.js
@@ -2,9 +2,7 @@
  * Tests for imgITools
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 /*
  * dumpToFile()
diff --git a/image/test/unit/test_private_channel.js b/image/test/unit/test_private_channel.js
index a6d981041b9e..008f6aad928c 100644
--- a/image/test/unit/test_private_channel.js
+++ b/image/test/unit/test_private_channel.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
 
 const ReferrerInfo = Components.Constructor(
diff --git a/intl/uconv/tests/unit/test_bug317216.js b/intl/uconv/tests/unit/test_bug317216.js
index cc10ef313e11..2e3e8878acba 100644
--- a/intl/uconv/tests/unit/test_bug317216.js
+++ b/intl/uconv/tests/unit/test_bug317216.js
@@ -9,9 +9,7 @@
  * UTF16 character and mid-surrogate pair
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const test = [
   // 0: Valid surrogate pair
diff --git a/intl/uconv/tests/unit/test_bug340714.js b/intl/uconv/tests/unit/test_bug340714.js
index fdd30543f2dd..2475ee5e90fe 100644
--- a/intl/uconv/tests/unit/test_bug340714.js
+++ b/intl/uconv/tests/unit/test_bug340714.js
@@ -11,9 +11,7 @@
  * is an eight-bit character.
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const beBOM = "%FE%FF";
 const leBOM = "%FF%FE";
diff --git a/intl/uconv/tests/unit/test_bug563618.js b/intl/uconv/tests/unit/test_bug563618.js
index f2d8a6e353cc..2fa077034495 100644
--- a/intl/uconv/tests/unit/test_bug563618.js
+++ b/intl/uconv/tests/unit/test_bug563618.js
@@ -4,9 +4,7 @@
  *
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const test = [
   // 0: 0x8e followed by hi byte, not valid JIS X 0201
diff --git a/intl/uconv/tests/unit/test_utf8_illegals.js b/intl/uconv/tests/unit/test_utf8_illegals.js
index 55aec6ab8c86..8712b4c3e82c 100644
--- a/intl/uconv/tests/unit/test_utf8_illegals.js
+++ b/intl/uconv/tests/unit/test_utf8_illegals.js
@@ -2,9 +2,7 @@
 
 var Cc = Components.Constructor;
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const tests = [
   {
diff --git a/js/xpconnect/tests/chrome/subscript.js b/js/xpconnect/tests/chrome/subscript.js
index c2708f6e9b4f..bcfbccafc9b2 100644
--- a/js/xpconnect/tests/chrome/subscript.js
+++ b/js/xpconnect/tests/chrome/subscript.js
@@ -1,4 +1,3 @@
-/* global base */
 var ns = {};
-Services.scriptloader.loadSubScript(base + "file_expandosharing.jsm", ns);
-var checkFromJSM = ns.checkFromJSM;
+Services.scriptloader.loadSubScript("resource://gre/modules/NetUtil.jsm", ns);
+var NetUtil = ns.NetUtil;
diff --git a/js/xpconnect/tests/chrome/test_chrometoSource.xhtml b/js/xpconnect/tests/chrome/test_chrometoSource.xhtml
index b9920603a046..843f125b878d 100644
--- a/js/xpconnect/tests/chrome/test_chrometoSource.xhtml
+++ b/js/xpconnect/tests/chrome/test_chrometoSource.xhtml
@@ -15,8 +15,6 @@
   <script type="application/javascript" src="outoflinexulscript.js"></script>
   <script type="application/javascript"><![CDATA[
 const {NetUtil} = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
-let base = /.*\//.exec(window.location.href)[0];
-const {checkFromJSM} = ChromeUtils.import(base + "file_expandosharing.jsm");
 
 function inlinefunction() {
          return 42;
@@ -29,22 +27,21 @@ is(src.charAt(src.length - 1), "}", "inline XUL source should end with '}'");
 src = outoflinefunction.toSource();
 isnot(src.indexOf("return 42"), -1, "out of line XUL script should have source")
 is(src.charAt(src.length - 1), "}", "out of line XUL source should end with '}'");
-src = checkFromJSM.toSource();
-isnot(src.indexOf("catch"), -1, "JSM should have source");
+src = NetUtil.asyncFetch.toSource();
+isnot(src.indexOf("return"), -1, "JSM should have source");
 var ns = {};
-Services.scriptloader.loadSubScript(base + "file_expandosharing.jsm", ns);
-src = ns.checkFromJSM.toSource();
-isnot(src.indexOf("catch"), -1, "subscript should have source");
+Services.scriptloader.loadSubScript("resource://gre/modules/NetUtil.jsm", ns);
+src = ns.NetUtil.asyncFetch.toSource();
+isnot(src.indexOf("return"), -1, "subscript should have source");
 
+var base = /.*\//.exec(window.location.href)[0];
 var reg = Cc["@mozilla.org/chrome/chrome-registry;1"].getService(Ci.nsIChromeRegistry);
 var resolvedBase = reg.convertChromeURL(NetUtil.newURI(base)).spec;
 
-ns = {
-  base,
-};
+ns = {};
 Services.scriptloader.loadSubScript(resolvedBase + "subscript.js", ns);
-src = ns.checkFromJSM.toSource();
-isnot(src.indexOf("catch"), -1, "subscript of a subscript should have source");
+src = ns.NetUtil.asyncFetch.toSource();
+isnot(src.indexOf("return"), -1, "subscript of a subscript should have source");
 
 ns = {};
 Services.scriptloader.loadSubScript(resolvedBase + "utf8_subscript.js", ns);
diff --git a/js/xpconnect/tests/unit/test_isModuleLoaded.js b/js/xpconnect/tests/unit/test_isModuleLoaded.js
index aaf67c13c716..338c283ad8fd 100644
--- a/js/xpconnect/tests/unit/test_isModuleLoaded.js
+++ b/js/xpconnect/tests/unit/test_isModuleLoaded.js
@@ -1,20 +1,22 @@
 function run_test() {
   // Existing module.
-  Assert.ok(!Cu.isModuleLoaded("resource://test/jsm_loaded-1.jsm"),
+  Assert.ok(Cu.isModuleLoaded("resource://gre/modules/NetUtil.jsm"),
             "isModuleLoaded returned correct value for non-loaded module");
-  ChromeUtils.import("resource://test/jsm_loaded-1.jsm");
-  Assert.ok(Cu.isModuleLoaded("resource://test/jsm_loaded-1.jsm"),
+  ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
+  Assert.ok(Cu.isModuleLoaded("resource://gre/modules/NetUtil.jsm"),
             "isModuleLoaded returned true after loading that module");
-  Cu.unload("resource://test/jsm_loaded-1.jsm");
-  Assert.ok(!Cu.isModuleLoaded("resource://test/jsm_loaded-1.jsm"),
+  Cu.unload("resource://gre/modules/NetUtil.jsm");
+  Assert.ok(!Cu.isModuleLoaded("resource://gre/modules/NetUtil.jsm"),
             "isModuleLoaded returned false after unloading that module");
 
   // Non-existing module
   Assert.ok(!Cu.isModuleLoaded("resource://gre/modules/non-existing-module.jsm"),
             "isModuleLoaded returned correct value for non-loaded module");
-  Assert.throws(
-    () => ChromeUtils.import("resource://gre/modules/non-existing-module.jsm"),
-    /NS_ERROR_FILE_NOT_FOUND/,
-    "Should have thrown while trying to load a non existing file"
-  );
+  try {
+    ChromeUtils.import("resource://gre/modules/non-existing-module.jsm");
+    Assert.ok(false,
+              "Should have thrown while trying to load a non existing file");
+  } catch (ex) {}
+  Assert.ok(!Cu.isModuleLoaded("resource://gre/modules/non-existing-module.jsm"),
+            "isModuleLoaded returned correct value for non-loaded module");
 }
diff --git a/js/xpconnect/tests/unit/test_lazyproxy.js b/js/xpconnect/tests/unit/test_lazyproxy.js
index 2cf90b339d61..a36fca45ad11 100644
--- a/js/xpconnect/tests/unit/test_lazyproxy.js
+++ b/js/xpconnect/tests/unit/test_lazyproxy.js
@@ -75,39 +75,39 @@ add_task(function test_lazy_proxy() {
 add_task(function test_module_version() {
   // Test that passing a string instead of an initialization function
   // makes this behave like a lazy module getter.
-  const TEST_FILE_URI = "resource://test/TestFile.jsm";
+  const NET_UTIL_URI = "resource://gre/modules/NetUtil.jsm";
   let underlyingObject;
 
-  Cu.unload(TEST_FILE_URI);
+  Cu.unload(NET_UTIL_URI);
 
   let lazyProxy = XPCOMUtils.defineLazyProxy(
     null,
-    "TestFile",
-    TEST_FILE_URI,
+    "NetUtil",
+    NET_UTIL_URI,
     null, /* no stubs */
     function untrapCallback(object) {
       underlyingObject = object;
     }
   );
 
-  Assert.ok(!Cu.isModuleLoaded(TEST_FILE_URI), "The NetUtil module was not loaded by the lazy proxy definition");
+  Assert.ok(!Cu.isModuleLoaded(NET_UTIL_URI), "The NetUtil module was not loaded by the lazy proxy definition");
 
   // Access the object, which will evaluate the proxy.
   lazyProxy.foo = "bar";
 
   // Module was loaded.
-  Assert.ok(Cu.isModuleLoaded(TEST_FILE_URI), "The NetUtil module was loaded");
+  Assert.ok(Cu.isModuleLoaded(NET_UTIL_URI), "The NetUtil module was loaded");
 
-  let { TestFile } = ChromeUtils.import(TEST_FILE_URI, {});
+  let { NetUtil } = ChromeUtils.import(NET_UTIL_URI, {});
 
   // Avoids a gigantic stringification in the logs.
-  Assert.ok(TestFile === underlyingObject, "The module loaded is the same as the one directly obtained by ChromeUtils.import");
+  Assert.ok(NetUtil === underlyingObject, "The module loaded is the same as the one directly obtained by ChromeUtils.import");
 
   // Proxy correctly passed the setter to the underlying object.
-  Assert.equal(TestFile.foo, "bar", "Proxy correctly passed the setter to the underlying object");
+  Assert.equal(NetUtil.foo, "bar", "Proxy correctly passed the setter to the underlying object");
 
   delete lazyProxy.foo;
 
   // Proxy correctly passed the delete operation to the underlying object.
-  Assert.ok(!TestFile.hasOwnProperty("foo"), "Proxy correctly passed the delete operation to the underlying object");
+  Assert.ok(!NetUtil.hasOwnProperty("foo"), "Proxy correctly passed the delete operation to the underlying object");
 });
diff --git a/js/xpconnect/tests/unit/test_nuke_webextension_wrappers.js b/js/xpconnect/tests/unit/test_nuke_webextension_wrappers.js
index 9cef1df05e89..34fd0511bc2d 100644
--- a/js/xpconnect/tests/unit/test_nuke_webextension_wrappers.js
+++ b/js/xpconnect/tests/unit/test_nuke_webextension_wrappers.js
@@ -1,6 +1,6 @@
 // See https://bugzilla.mozilla.org/show_bug.cgi?id=1273251
 
-const {NetUtil} = ChromeUtils.importESModule("resource://gre/modules/NetUtil.sys.mjs");
+const {NetUtil} = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 ChromeUtils.importESModule("resource://gre/modules/Timer.sys.mjs");
 const {TestUtils} = ChromeUtils.importESModule("resource://testing-common/TestUtils.sys.mjs");
 
diff --git a/js/xpconnect/tests/unit/test_uawidget_scope.js b/js/xpconnect/tests/unit/test_uawidget_scope.js
index 744f977cb702..ede9d656cd7e 100644
--- a/js/xpconnect/tests/unit/test_uawidget_scope.js
+++ b/js/xpconnect/tests/unit/test_uawidget_scope.js
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 ChromeUtils.importESModule("resource://gre/modules/Timer.sys.mjs");
-const {NetUtil} = ChromeUtils.importESModule("resource://gre/modules/NetUtil.sys.mjs");
+const {NetUtil} = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const {TestUtils} = ChromeUtils.importESModule("resource://testing-common/TestUtils.sys.mjs");
 
 function getWindowlessBrowser(url) {
diff --git a/js/xpconnect/tests/unit/test_unload.js b/js/xpconnect/tests/unit/test_unload.js
index 13e2e0c63efb..6d6c7f4c691a 100644
--- a/js/xpconnect/tests/unit/test_unload.js
+++ b/js/xpconnect/tests/unit/test_unload.js
@@ -4,25 +4,25 @@
 
 function run_test() {
   var scope1 = {};
-  var exports1 = ChromeUtils.import("resource://test/TestBlob.jsm", scope1);
+  var exports1 = ChromeUtils.import("resource://gre/modules/NetUtil.jsm", scope1);
 
   var scope2 = {};
-  var exports2 = ChromeUtils.import("resource://test/TestBlob.jsm", scope2);
+  var exports2 = ChromeUtils.import("resource://gre/modules/NetUtil.jsm", scope2);
 
   Assert.ok(exports1 === exports2);
-  Assert.ok(scope1.TestBlob === scope2.TestBlob);
+  Assert.ok(scope1.NetUtil === scope2.NetUtil);
 
-  Cu.unload("resource://test/TestBlob.jsm");
+  Cu.unload("resource://gre/modules/NetUtil.jsm");
 
   var scope3 = {};
-  var exports3 = ChromeUtils.import("resource://test/TestBlob.jsm", scope3);
+  var exports3 = ChromeUtils.import("resource://gre/modules/NetUtil.jsm", scope3);
 
   Assert.equal(false, exports1 === exports3);
-  Assert.equal(false, scope1.TestBlob === scope3.TestBlob);
+  Assert.equal(false, scope1.NetUtil === scope3.NetUtil);
 
   // When the jsm was unloaded, the value of all its global's properties were
   // set to undefined. While it must be safe (not crash) to call into the
   // module, we expect it to throw an error (e.g., when trying to use Ci).
-  try { scope1.TestBlob.doTest(() => {}); } catch (e) {}
-  try { scope3.TestBlob.doTest(() => {}); } catch (e) {}
+  try { scope1.NetUtil.newURI("http://www.example.com"); } catch (e) {}
+  try { scope3.NetUtil.newURI("http://www.example.com"); } catch (e) {}
 }
diff --git a/layout/tools/reftest/manifest.jsm b/layout/tools/reftest/manifest.jsm
index d8351172f3ce..476b04317b4c 100644
--- a/layout/tools/reftest/manifest.jsm
+++ b/layout/tools/reftest/manifest.jsm
@@ -30,7 +30,7 @@ const {
 
     g,
 } = ChromeUtils.import("resource://reftest/globals.jsm");
-const { NetUtil } = ChromeUtils.importESModule("resource://gre/modules/NetUtil.sys.mjs");
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { AppConstants } = ChromeUtils.importESModule(
     "resource://gre/modules/AppConstants.sys.mjs"
 );
diff --git a/modules/libjar/test/unit/test_bug1328865.js b/modules/libjar/test/unit/test_bug1328865.js
index 81be250ed113..3c973cb77cc9 100644
--- a/modules/libjar/test/unit/test_bug1328865.js
+++ b/modules/libjar/test/unit/test_bug1328865.js
@@ -4,9 +4,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Check that reading non existant inner jars results in the right error
 
diff --git a/modules/libjar/test/unit/test_bug370103.js b/modules/libjar/test/unit/test_bug370103.js
index 7b71a512cdd4..d9d0e3e6a295 100644
--- a/modules/libjar/test/unit/test_bug370103.js
+++ b/modules/libjar/test/unit/test_bug370103.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Regression test for bug 370103 - crash when passing a null listener to
 // nsIChannel.asyncOpen
diff --git a/modules/libjar/test/unit/test_bug589292.js b/modules/libjar/test/unit/test_bug589292.js
index 73f3866300c0..07b43d297338 100644
--- a/modules/libjar/test/unit/test_bug589292.js
+++ b/modules/libjar/test/unit/test_bug589292.js
@@ -1,8 +1,6 @@
 // Make sure we behave appropriately when asking for content-disposition
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const path = "data/test_bug589292.zip";
 
diff --git a/modules/libjar/test/unit/test_bug597702.js b/modules/libjar/test/unit/test_bug597702.js
index d7ffe6d36027..8514c593f17d 100644
--- a/modules/libjar/test/unit/test_bug597702.js
+++ b/modules/libjar/test/unit/test_bug597702.js
@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Check that reading non existant inner jars results in the right error
 
diff --git a/modules/libjar/test/unit/test_bug637286.js b/modules/libjar/test/unit/test_bug637286.js
index 6b4e8ee1c5ac..114e6b19f226 100644
--- a/modules/libjar/test/unit/test_bug637286.js
+++ b/modules/libjar/test/unit/test_bug637286.js
@@ -2,9 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Check that the zip cache can expire entries from nested jars
 
diff --git a/modules/libjar/test/unit/test_bug658093.js b/modules/libjar/test/unit/test_bug658093.js
index a7c23740d89c..92b765477577 100644
--- a/modules/libjar/test/unit/test_bug658093.js
+++ b/modules/libjar/test/unit/test_bug658093.js
@@ -2,9 +2,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Check that we don't crash on reading a directory entry signature
 
diff --git a/modules/libjar/test/unit/test_empty_jar_telemetry.js b/modules/libjar/test/unit/test_empty_jar_telemetry.js
index 895e88ff6551..f63b4028d7dd 100644
--- a/modules/libjar/test/unit/test_empty_jar_telemetry.js
+++ b/modules/libjar/test/unit/test_empty_jar_telemetry.js
@@ -4,9 +4,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const { TelemetryTestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/TelemetryTestUtils.sys.mjs"
diff --git a/modules/libjar/test/unit/test_jarchannel.js b/modules/libjar/test/unit/test_jarchannel.js
index 9d3a571b6356..1af6d1885412 100644
--- a/modules/libjar/test/unit/test_jarchannel.js
+++ b/modules/libjar/test/unit/test_jarchannel.js
@@ -8,9 +8,7 @@
 
 const { Constructor: ctor } = Components;
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const ios = Services.io;
 const dirSvc = Services.dirsvc;
diff --git a/modules/libjar/test/unit/test_not_found.js b/modules/libjar/test/unit/test_not_found.js
index a014ce6f2f6d..90c298e64acf 100644
--- a/modules/libjar/test/unit/test_not_found.js
+++ b/modules/libjar/test/unit/test_not_found.js
@@ -1,8 +1,6 @@
 // Should report file not found on non-existent files
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const path = "data/test_bug333423.zip";
 
 function run_test() {
diff --git a/modules/libjar/zipwriter/test/unit/test_asyncadd.js b/modules/libjar/zipwriter/test/unit/test_asyncadd.js
index 0259a7953cd7..ef70d292d7d9 100644
--- a/modules/libjar/zipwriter/test/unit/test_asyncadd.js
+++ b/modules/libjar/zipwriter/test/unit/test_asyncadd.js
@@ -3,9 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // Values taken from using zipinfo to list the test.zip contents
 var TESTS = [
diff --git a/netwerk/base/NetUtil.sys.mjs b/netwerk/base/NetUtil.jsm
similarity index 99%
rename from netwerk/base/NetUtil.sys.mjs
rename to netwerk/base/NetUtil.jsm
index 679c9979a79a..8c5d1bcd2507 100644
--- a/netwerk/base/NetUtil.sys.mjs
+++ b/netwerk/base/NetUtil.jsm
@@ -4,6 +4,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+var EXPORTED_SYMBOLS = ["NetUtil"];
+
 /**
  * Necko utilities
  */
@@ -22,7 +24,7 @@ const BinaryInputStream = Components.Constructor(
 // //////////////////////////////////////////////////////////////////////////////
 // // NetUtil Object
 
-export var NetUtil = {
+var NetUtil = {
   /**
    * Function to perform simple async copying from aSource (an input stream)
    * to aSink (an output stream).  The copy will happen on some background
diff --git a/netwerk/base/moz.build b/netwerk/base/moz.build
index d35714df2133..b0d729ea90ee 100644
--- a/netwerk/base/moz.build
+++ b/netwerk/base/moz.build
@@ -303,7 +303,7 @@ elif CONFIG["OS_ARCH"] == "Linux":
     ]
 
 EXTRA_JS_MODULES += [
-    "NetUtil.sys.mjs",
+    "NetUtil.jsm",
 ]
 
 DIRS += ["mozurl", "rust-helper", "http-sfv"]
diff --git a/netwerk/cookie/test/unit/test_bug1155169.js b/netwerk/cookie/test/unit/test_bug1155169.js
index 20856d7b5058..de2cd50ab61d 100644
--- a/netwerk/cookie/test/unit/test_bug1155169.js
+++ b/netwerk/cookie/test/unit/test_bug1155169.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const URI = Services.io.newURI("http://example.org/");
 
diff --git a/netwerk/cookie/test/unit/test_bug643051.js b/netwerk/cookie/test/unit/test_bug643051.js
index 35b37a5889ea..d06f37587765 100644
--- a/netwerk/cookie/test/unit/test_bug643051.js
+++ b/netwerk/cookie/test/unit/test_bug643051.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { CookieXPCShellUtils } = ChromeUtils.importESModule(
   "resource://testing-common/CookieXPCShellUtils.sys.mjs"
 );
diff --git a/netwerk/cookie/test/unit/test_eviction.js b/netwerk/cookie/test/unit/test_eviction.js
index 8c0073a107ae..f694cc80aa62 100644
--- a/netwerk/cookie/test/unit/test_eviction.js
+++ b/netwerk/cookie/test/unit/test_eviction.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const BASE_HOST = "example.org";
 
diff --git a/netwerk/cookie/test/unit/test_getCookieSince.js b/netwerk/cookie/test/unit/test_getCookieSince.js
index e58624b6a123..6d419860ed6c 100644
--- a/netwerk/cookie/test/unit/test_getCookieSince.js
+++ b/netwerk/cookie/test/unit/test_getCookieSince.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function setCookie(name, url) {
   let value = `${name}=${Math.random()}; Path=/; Max-Age=1000; sameSite=none; Secure`;
diff --git a/netwerk/cookie/test/unit/test_parser_0001.js b/netwerk/cookie/test/unit/test_parser_0001.js
index acc2e919ef6b..60a65b971817 100644
--- a/netwerk/cookie/test/unit/test_parser_0001.js
+++ b/netwerk/cookie/test/unit/test_parser_0001.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function inChildProcess() {
   return Services.appinfo.processType != Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
diff --git a/netwerk/cookie/test/unit/test_parser_0019.js b/netwerk/cookie/test/unit/test_parser_0019.js
index 7ba0d4ef7996..f2c883cb32a2 100644
--- a/netwerk/cookie/test/unit/test_parser_0019.js
+++ b/netwerk/cookie/test/unit/test_parser_0019.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function inChildProcess() {
   return Services.appinfo.processType != Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
diff --git a/netwerk/cookie/test/unit/test_rawSameSite.js b/netwerk/cookie/test/unit/test_rawSameSite.js
index ee709dbe7ea4..7cf10d5440c9 100644
--- a/netwerk/cookie/test/unit/test_rawSameSite.js
+++ b/netwerk/cookie/test/unit/test_rawSameSite.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function inChildProcess() {
   return Services.appinfo.processType != Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
diff --git a/netwerk/cookie/test/unit/test_schemeMap.js b/netwerk/cookie/test/unit/test_schemeMap.js
index 041c24033a8f..8802fd7e1f0b 100644
--- a/netwerk/cookie/test/unit/test_schemeMap.js
+++ b/netwerk/cookie/test/unit/test_schemeMap.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function inChildProcess() {
   return Services.appinfo.processType != Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT;
diff --git a/netwerk/test/browser/cookie_filtering_helper.sys.mjs b/netwerk/test/browser/cookie_filtering_helper.sys.mjs
index 5e6cd8299e4f..f3db10ffb353 100644
--- a/netwerk/test/browser/cookie_filtering_helper.sys.mjs
+++ b/netwerk/test/browser/cookie_filtering_helper.sys.mjs
@@ -9,8 +9,7 @@
 /* global ContentTaskUtils, content */
 
 const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
-
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const info = console.log;
 
 export var HTTPS_EXAMPLE_ORG = "https://example.org";
diff --git a/netwerk/test/httpserver/test/head_utils.js b/netwerk/test/httpserver/test/head_utils.js
index 8acce7bb8821..76e7ed6fd38e 100644
--- a/netwerk/test/httpserver/test/head_utils.js
+++ b/netwerk/test/httpserver/test/head_utils.js
@@ -16,9 +16,7 @@ var linDEBUG = true;
 var { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 /**
  * Constructs a new nsHttpServer instance.  This function is intended to
diff --git a/netwerk/test/unit/head_cookies.js b/netwerk/test/unit/head_cookies.js
index d936b23c7ed5..2cb9390c68de 100644
--- a/netwerk/test/unit/head_cookies.js
+++ b/netwerk/test/unit/head_cookies.js
@@ -6,9 +6,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { CookieXPCShellUtils } = ChromeUtils.importESModule(
   "resource://testing-common/CookieXPCShellUtils.sys.mjs"
 );
diff --git a/netwerk/test/unit_ipc/head_channels_clone.js b/netwerk/test/unit_ipc/head_channels_clone.js
index be87bc8829d7..f287c6f76fc9 100644
--- a/netwerk/test/unit_ipc/head_channels_clone.js
+++ b/netwerk/test/unit_ipc/head_channels_clone.js
@@ -2,9 +2,7 @@
 // Load standard base class for network tests into child process
 //
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/netwerk/test/unit_ipc/head_http3_clone.js b/netwerk/test/unit_ipc/head_http3_clone.js
index 51e0c8017e07..4b4e1155efa7 100644
--- a/netwerk/test/unit_ipc/head_http3_clone.js
+++ b/netwerk/test/unit_ipc/head_http3_clone.js
@@ -1,8 +1,6 @@
 /* import-globals-from ../unit/head_http3.js */
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/netwerk/test/unit_ipc/head_trr_clone.js b/netwerk/test/unit_ipc/head_trr_clone.js
index 9516e83f7fa5..e52c380f1907 100644
--- a/netwerk/test/unit_ipc/head_trr_clone.js
+++ b/netwerk/test/unit_ipc/head_trr_clone.js
@@ -1,8 +1,6 @@
 /* import-globals-from ../unit/head_trr.js */
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/remote/cdp/domains/parent/Emulation.sys.mjs b/remote/cdp/domains/parent/Emulation.sys.mjs
index 21aaf2f96501..8cb01b16ac57 100644
--- a/remote/cdp/domains/parent/Emulation.sys.mjs
+++ b/remote/cdp/domains/parent/Emulation.sys.mjs
@@ -2,12 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
 import { Domain } from "chrome://remote/content/cdp/domains/Domain.sys.mjs";
 
 const lazy = {};
 
-ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 const MAX_WINDOW_SIZE = 10000000;
diff --git a/remote/cdp/observers/NetworkObserver.sys.mjs b/remote/cdp/observers/NetworkObserver.sys.mjs
index c90ac7463bee..a85aa2d44fe9 100644
--- a/remote/cdp/observers/NetworkObserver.sys.mjs
+++ b/remote/cdp/observers/NetworkObserver.sys.mjs
@@ -9,12 +9,15 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   CommonUtils: "resource://services-common/utils.sys.mjs",
   EventEmitter: "resource://gre/modules/EventEmitter.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 
   ChannelEventSinkFactory:
     "chrome://remote/content/cdp/observers/ChannelEventSink.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 XPCOMUtils.defineLazyServiceGetter(
   lazy,
   "gActivityDistributor",
diff --git a/security/manager/pki/resources/content/certManager.js b/security/manager/pki/resources/content/certManager.js
index b1fcaff30f29..00bb29f307ca 100644
--- a/security/manager/pki/resources/content/certManager.js
+++ b/security/manager/pki/resources/content/certManager.js
@@ -6,9 +6,7 @@
 
 const gCertFileTypes = "*.p7b; *.crt; *.cert; *.cer; *.pem; *.der";
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 var key;
 
diff --git a/security/manager/ssl/tests/unit/head_psm.js b/security/manager/ssl/tests/unit/head_psm.js
index 61a01601ebbb..bb770a1b6393 100644
--- a/security/manager/ssl/tests/unit/head_psm.js
+++ b/security/manager/ssl/tests/unit/head_psm.js
@@ -17,9 +17,7 @@ const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
 const { MockRegistrar } = ChromeUtils.importESModule(
   "resource://testing-common/MockRegistrar.sys.mjs"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { PromiseUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/PromiseUtils.sys.mjs"
 );
diff --git a/security/manager/tools/genRootCAHashes.js b/security/manager/tools/genRootCAHashes.js
index be0233a0c094..fbe6b847de9d 100644
--- a/security/manager/tools/genRootCAHashes.js
+++ b/security/manager/tools/genRootCAHashes.js
@@ -15,9 +15,7 @@ const CertDb = Cc[nsX509CertDB].getService(Ci.nsIX509CertDB);
 const { FileUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/FileUtils.sys.mjs"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { CommonUtils } = ChromeUtils.importESModule(
   "resource://services-common/utils.sys.mjs"
 );
diff --git a/services/common/logmanager.sys.mjs b/services/common/logmanager.sys.mjs
index be1c850db1ba..178228f3e6d7 100644
--- a/services/common/logmanager.sys.mjs
+++ b/services/common/logmanager.sys.mjs
@@ -9,8 +9,12 @@ const lazy = {};
 
 ChromeUtils.defineESModuleGetters(lazy, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 import { Preferences } from "resource://gre/modules/Preferences.sys.mjs";
 
diff --git a/services/common/rest.sys.mjs b/services/common/rest.sys.mjs
index 4d1e1940579e..a6f94242112b 100644
--- a/services/common/rest.sys.mjs
+++ b/services/common/rest.sys.mjs
@@ -2,8 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
-
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 import { Log } from "resource://gre/modules/Log.sys.mjs";
 import { PromiseUtils } from "resource://gre/modules/PromiseUtils.sys.mjs";
 
diff --git a/services/common/tests/unit/head_helpers.js b/services/common/tests/unit/head_helpers.js
index b65b10ebcecb..1947ece254f6 100644
--- a/services/common/tests/unit/head_helpers.js
+++ b/services/common/tests/unit/head_helpers.js
@@ -41,9 +41,7 @@ var { getTestLogger, initTestLogging } = ChromeUtils.importESModule(
 var { MockRegistrar } = ChromeUtils.importESModule(
   "resource://testing-common/MockRegistrar.sys.mjs"
 );
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function do_check_empty(obj) {
   do_check_attribute_count(obj, 0);
diff --git a/services/sync/tests/unit/head_helpers.js b/services/sync/tests/unit/head_helpers.js
index ed60dbd65a22..dbfa6f3269fb 100644
--- a/services/sync/tests/unit/head_helpers.js
+++ b/services/sync/tests/unit/head_helpers.js
@@ -76,9 +76,7 @@ XPCOMUtils.defineLazyGetter(this, "SyncPingSchema", function () {
   let { FileUtils } = ChromeUtils.importESModule(
     "resource://gre/modules/FileUtils.sys.mjs"
   );
-  let { NetUtil } = ChromeUtils.importESModule(
-    "resource://gre/modules/NetUtil.sys.mjs"
-  );
+  let { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
   let stream = Cc["@mozilla.org/network/file-input-stream;1"].createInstance(
     Ci.nsIFileInputStream
   );
diff --git a/services/sync/tps/extensions/tps/resource/tps.jsm b/services/sync/tps/extensions/tps/resource/tps.jsm
index 4ca454c1a69f..ceee24d3dc2e 100644
--- a/services/sync/tps/extensions/tps/resource/tps.jsm
+++ b/services/sync/tps/extensions/tps/resource/tps.jsm
@@ -61,7 +61,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
   Livemark: "resource://tps/modules/bookmarks.sys.mjs",
   Log: "resource://gre/modules/Log.sys.mjs",
   Logger: "resource://tps/logger.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   Password: "resource://tps/modules/passwords.sys.mjs",
   PasswordValidator: "resource://services-sync/engines/passwords.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
@@ -88,6 +87,12 @@ XPCOMUtils.defineLazyGetter(lazy, "gTextDecoder", () => {
   return new TextDecoder();
 });
 
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
+
 // Options for wiping data during a sync
 const SYNC_RESET_CLIENT = "resetClient";
 const SYNC_WIPE_CLIENT = "wipeClient";
diff --git a/taskcluster/docker/periodic-updates/scripts/genHPKPStaticPins.js b/taskcluster/docker/periodic-updates/scripts/genHPKPStaticPins.js
index 0d0757d55b91..af297374b187 100644
--- a/taskcluster/docker/periodic-updates/scripts/genHPKPStaticPins.js
+++ b/taskcluster/docker/periodic-updates/scripts/genHPKPStaticPins.js
@@ -19,9 +19,7 @@ if (arguments.length != 2) {
   );
 }
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { FileUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/FileUtils.sys.mjs"
 );
diff --git a/testing/mochitest/chrome-harness.js b/testing/mochitest/chrome-harness.js
index 7c506a63aa14..cb224a3c2f2c 100644
--- a/testing/mochitest/chrome-harness.js
+++ b/testing/mochitest/chrome-harness.js
@@ -4,9 +4,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 /* import-globals-from manifestLibrary.js */
 
diff --git a/testing/mochitest/document-builder.sjs b/testing/mochitest/document-builder.sjs
index 7af89e1f7194..b8c9ef21e7e9 100644
--- a/testing/mochitest/document-builder.sjs
+++ b/testing/mochitest/document-builder.sjs
@@ -4,9 +4,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 Cu.importGlobalProperties(["URLSearchParams"]);
 
 function loadHTMLFromFile(path) {
diff --git a/testing/mochitest/server.js b/testing/mochitest/server.js
index bc547664b943..6942fb0f7506 100644
--- a/testing/mochitest/server.js
+++ b/testing/mochitest/server.js
@@ -700,9 +700,7 @@ function regularListing(metadata, response) {
  * it into an object for creating a table of clickable links for each test.
  */
 function convertManifestToTestLinks(root, manifest) {
-  const { NetUtil } = ChromeUtils.importESModule(
-    "resource://gre/modules/NetUtil.sys.mjs"
-  );
+  const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
   var manifestFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
   manifestFile.initWithFile(serverBasePath);
diff --git a/testing/specialpowers/content/SpecialPowersChild.sys.mjs b/testing/specialpowers/content/SpecialPowersChild.sys.mjs
index 4b5d1989288f..0981d52e88a6 100644
--- a/testing/specialpowers/content/SpecialPowersChild.sys.mjs
+++ b/testing/specialpowers/content/SpecialPowersChild.sys.mjs
@@ -15,13 +15,17 @@ ChromeUtils.defineESModuleGetters(lazy, {
   MockColorPicker: "resource://specialpowers/MockColorPicker.sys.mjs",
   MockFilePicker: "resource://specialpowers/MockFilePicker.sys.mjs",
   MockPermissionPrompt: "resource://specialpowers/MockPermissionPrompt.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PerTestCoverageUtils:
     "resource://testing-common/PerTestCoverageUtils.sys.mjs",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
   SpecialPowersSandbox: "resource://specialpowers/SpecialPowersSandbox.sys.mjs",
   WrapPrivileged: "resource://specialpowers/WrapPrivileged.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 
 Cu.crashIfNotInAutomation();
diff --git a/testing/talos/talos/bootstrap.js b/testing/talos/talos/bootstrap.js
index 7acad7ea905e..20bd203d13b0 100644
--- a/testing/talos/talos/bootstrap.js
+++ b/testing/talos/talos/bootstrap.js
@@ -18,9 +18,7 @@
 const { AppConstants } = ChromeUtils.importESModule(
   "resource://gre/modules/AppConstants.sys.mjs"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const windowTracker = {
   init() {
diff --git a/testing/talos/talos/pageloader/chrome/Profiler.js b/testing/talos/talos/pageloader/chrome/Profiler.js
index 642cfd500c72..da7e66c0fc98 100644
--- a/testing/talos/talos/pageloader/chrome/Profiler.js
+++ b/testing/talos/talos/pageloader/chrome/Profiler.js
@@ -128,8 +128,8 @@ var Profiler;
           profile => {
             let profileFile = profiler_dir + "/" + currentTest + ".profile";
 
-            const { NetUtil } = ChromeUtils.importESModule(
-              "resource://gre/modules/NetUtil.sys.mjs"
+            const { NetUtil } = ChromeUtils.import(
+              "resource://gre/modules/NetUtil.jsm"
             );
             const { FileUtils } = ChromeUtils.importESModule(
               "resource://gre/modules/FileUtils.sys.mjs"
diff --git a/testing/xpcshell/head.js b/testing/xpcshell/head.js
index 8cdc834d435f..0ee1ec3bcb51 100644
--- a/testing/xpcshell/head.js
+++ b/testing/xpcshell/head.js
@@ -52,8 +52,8 @@ let { PromiseTestUtils: _PromiseTestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/PromiseTestUtils.sys.mjs"
 );
 
-let { NetUtil: _NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
+let { NetUtil: _NetUtil } = ChromeUtils.import(
+  "resource://gre/modules/NetUtil.jsm"
 );
 
 let { XPCOMUtils: _XPCOMUtils } = ChromeUtils.importESModule(
diff --git a/toolkit/components/DefaultCLH.sys.mjs b/toolkit/components/DefaultCLH.jsm
similarity index 97%
rename from toolkit/components/DefaultCLH.sys.mjs
rename to toolkit/components/DefaultCLH.jsm
index 2603c5a50cd0..36b78d72378d 100644
--- a/toolkit/components/DefaultCLH.sys.mjs
+++ b/toolkit/components/DefaultCLH.jsm
@@ -24,7 +24,7 @@ function getDirectoryService() {
   return Cc["@mozilla.org/file/directory_service;1"].getService(nsIProperties);
 }
 
-export function nsDefaultCLH() {}
+function nsDefaultCLH() {}
 nsDefaultCLH.prototype = {
   classID: Components.ID("{6ebc941a-f2ff-4d56-b3b6-f7d0b9d73344}"),
 
@@ -111,3 +111,5 @@ nsDefaultCLH.prototype = {
 
   helpInfo: "",
 };
+
+var EXPORTED_SYMBOLS = ["nsDefaultCLH"];
diff --git a/toolkit/components/aboutmemory/content/aboutMemory.js b/toolkit/components/aboutmemory/content/aboutMemory.js
index 93937c641382..c1b7986781ce 100644
--- a/toolkit/components/aboutmemory/content/aboutMemory.js
+++ b/toolkit/components/aboutmemory/content/aboutMemory.js
@@ -32,9 +32,7 @@ const UNITS_PERCENTAGE = Ci.nsIMemoryReporter.UNITS_PERCENTAGE;
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 ChromeUtils.defineESModuleGetters(this, {
   Downloads: "resource://gre/modules/Downloads.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
diff --git a/toolkit/components/components.conf b/toolkit/components/components.conf
index 2d4073dcf0e4..473f3af2a3bb 100644
--- a/toolkit/components/components.conf
+++ b/toolkit/components/components.conf
@@ -8,7 +8,7 @@ Classes = [
     {
         'cid': '{6ebc941a-f2ff-4d56-b3b6-f7d0b9d73344}',
         'contract_ids': ['@mozilla.org/toolkit/default-clh;1'],
-        'esModule': 'resource://gre/modules/DefaultCLH.sys.mjs',
+        'jsm': 'resource://gre/modules/DefaultCLH.jsm',
         'constructor': 'nsDefaultCLH',
         'categories': {'command-line-handler': 'y-default'},
     },
diff --git a/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs b/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs
index 75cd3e0936e0..a0c0357db353 100644
--- a/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs
+++ b/toolkit/components/contextualidentity/ContextualIdentityService.sys.mjs
@@ -30,8 +30,12 @@ ChromeUtils.defineESModuleGetters(lazy, {
   AsyncShutdown: "resource://gre/modules/AsyncShutdown.sys.mjs",
   DeferredTask: "resource://gre/modules/DeferredTask.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 function _TabRemovalObserver(resolver, remoteTabIds) {
   this._resolver = resolver;
diff --git a/toolkit/components/downloads/DownloadCore.sys.mjs b/toolkit/components/downloads/DownloadCore.sys.mjs
index 715dadaaa597..cca7e59fe7ea 100644
--- a/toolkit/components/downloads/DownloadCore.sys.mjs
+++ b/toolkit/components/downloads/DownloadCore.sys.mjs
@@ -18,10 +18,13 @@ ChromeUtils.defineESModuleGetters(lazy, {
   DownloadPaths: "resource://gre/modules/DownloadPaths.sys.mjs",
   E10SUtils: "resource://gre/modules/E10SUtils.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PromiseUtils: "resource://gre/modules/PromiseUtils.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 XPCOMUtils.defineLazyServiceGetter(
   lazy,
   "gExternalAppLauncher",
diff --git a/toolkit/components/downloads/DownloadIntegration.sys.mjs b/toolkit/components/downloads/DownloadIntegration.sys.mjs
index 698775e29443..b2caad456ee2 100644
--- a/toolkit/components/downloads/DownloadIntegration.sys.mjs
+++ b/toolkit/components/downloads/DownloadIntegration.sys.mjs
@@ -22,8 +22,12 @@ ChromeUtils.defineESModuleGetters(lazy, {
   DownloadStore: "resource://gre/modules/DownloadStore.sys.mjs",
   DownloadUIHelper: "resource://gre/modules/DownloadUIHelper.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 XPCOMUtils.defineLazyServiceGetter(
   lazy,
diff --git a/toolkit/components/downloads/test/unit/head.js b/toolkit/components/downloads/test/unit/head.js
index c2c4b6474683..44364c1cbfc4 100644
--- a/toolkit/components/downloads/test/unit/head.js
+++ b/toolkit/components/downloads/test/unit/head.js
@@ -26,7 +26,6 @@ ChromeUtils.defineESModuleGetters(this, {
   FileTestUtils: "resource://testing-common/FileTestUtils.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
   MockRegistrar: "resource://testing-common/MockRegistrar.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
   PromiseUtils: "resource://gre/modules/PromiseUtils.sys.mjs",
   TelemetryTestUtils: "resource://testing-common/TelemetryTestUtils.sys.mjs",
@@ -35,6 +34,7 @@ ChromeUtils.defineESModuleGetters(this, {
 
 XPCOMUtils.defineLazyModuleGetters(this, {
   HttpServer: "resource://testing-common/httpd.js",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 XPCOMUtils.defineLazyServiceGetter(
diff --git a/toolkit/components/extensions/Extension.jsm b/toolkit/components/extensions/Extension.jsm
index 44e20c376de5..1cf63b1f4dfe 100644
--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -58,7 +58,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
   Log: "resource://gre/modules/Log.sys.mjs",
   permissionToL10nId:
     "resource://gre/modules/ExtensionPermissionMessages.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   SITEPERMS_ADDON_TYPE:
     "resource://gre/modules/addons/siteperms-addon-utils.sys.mjs",
 });
@@ -77,6 +76,7 @@ XPCOMUtils.defineLazyModuleGetters(lazy, {
   extensionStorageSync: "resource://gre/modules/ExtensionStorageSync.jsm",
   ExtensionTelemetry: "resource://gre/modules/ExtensionTelemetry.jsm",
   LightweightThemeManager: "resource://gre/modules/LightweightThemeManager.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   Schemas: "resource://gre/modules/Schemas.jsm",
   ServiceWorkerCleanUp: "resource://gre/modules/ServiceWorkerCleanUp.jsm",
 });
diff --git a/toolkit/components/extensions/Schemas.jsm b/toolkit/components/extensions/Schemas.jsm
index ef65cd131d5b..9eeb928571e9 100644
--- a/toolkit/components/extensions/Schemas.jsm
+++ b/toolkit/components/extensions/Schemas.jsm
@@ -24,8 +24,12 @@ ChromeUtils.defineModuleGetter(
   "ExtensionParent",
   "resource://gre/modules/ExtensionParent.jsm"
 );
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   ShortcutUtils: "resource://gre/modules/ShortcutUtils.sys.mjs",
 });
 XPCOMUtils.defineLazyServiceGetter(
diff --git a/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js b/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js
index 2194e156dd81..dfec90b3e09f 100644
--- a/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js
+++ b/toolkit/components/extensions/test/mochitest/head_unlimitedStorage.js
@@ -5,8 +5,8 @@
 /* exported checkSitePermissions */
 
 const { Services } = SpecialPowers;
-const { NetUtil } = SpecialPowers.ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
+const { NetUtil } = SpecialPowers.ChromeUtils.import(
+  "resource://gre/modules/NetUtil.jsm"
 );
 
 function checkSitePermissions(uuid, expectedPermAction, assertMessage) {
diff --git a/toolkit/components/extensions/test/xpcshell/head.js b/toolkit/components/extensions/test/xpcshell/head.js
index b5867fe7696d..891cc96c3010 100644
--- a/toolkit/components/extensions/test/xpcshell/head.js
+++ b/toolkit/components/extensions/test/xpcshell/head.js
@@ -27,7 +27,6 @@ var { AddonTestUtils, MockAsyncShutdown } = ChromeUtils.import(
 ChromeUtils.defineESModuleGetters(this, {
   ContentTask: "resource://testing-common/ContentTask.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PromiseTestUtils: "resource://testing-common/PromiseTestUtils.sys.mjs",
 });
 
@@ -37,6 +36,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   ExtensionParent: "resource://gre/modules/ExtensionParent.jsm",
   ExtensionTestUtils: "resource://testing-common/ExtensionXPCShellUtils.jsm",
   MessageChannel: "resource://testing-common/MessageChannel.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   Schemas: "resource://gre/modules/Schemas.jsm",
 });
 
diff --git a/toolkit/components/mediasniffer/test/unit/test_mediasniffer.js b/toolkit/components/mediasniffer/test/unit/test_mediasniffer.js
index ee2fbdc25c59..b33ec2f590ac 100644
--- a/toolkit/components/mediasniffer/test/unit/test_mediasniffer.js
+++ b/toolkit/components/mediasniffer/test/unit/test_mediasniffer.js
@@ -3,9 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const PATH = "/file.meh";
 var httpserver = new HttpServer();
diff --git a/toolkit/components/mediasniffer/test/unit/test_mediasniffer_ext.js b/toolkit/components/mediasniffer/test/unit/test_mediasniffer_ext.js
index 7885528f6893..5439e5b51dba 100644
--- a/toolkit/components/mediasniffer/test/unit/test_mediasniffer_ext.js
+++ b/toolkit/components/mediasniffer/test/unit/test_mediasniffer_ext.js
@@ -11,9 +11,7 @@ var BinaryOutputStream = CC(
 );
 
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 var httpserver = new HttpServer();
 
diff --git a/toolkit/components/moz.build b/toolkit/components/moz.build
index f8e0094e600e..878dcea32396 100644
--- a/toolkit/components/moz.build
+++ b/toolkit/components/moz.build
@@ -117,7 +117,7 @@ if CONFIG["MOZ_WIDGET_TOOLKIT"] == "windows":
 
 if CONFIG["MOZ_WIDGET_TOOLKIT"] != "android":
     EXTRA_JS_MODULES += [
-        "DefaultCLH.sys.mjs",
+        "DefaultCLH.jsm",
     ]
 
     XPCOM_MANIFESTS += [
diff --git a/toolkit/components/mozprotocol/MozProtocolHandler.sys.mjs b/toolkit/components/mozprotocol/MozProtocolHandler.sys.mjs
index fc00c1c09aa6..6629f274d838 100644
--- a/toolkit/components/mozprotocol/MozProtocolHandler.sys.mjs
+++ b/toolkit/components/mozprotocol/MozProtocolHandler.sys.mjs
@@ -4,7 +4,7 @@
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 export function MozProtocolHandler() {
   XPCOMUtils.defineLazyPreferenceGetter(
diff --git a/toolkit/components/nimbus/test/NimbusTestUtils.sys.mjs b/toolkit/components/nimbus/test/NimbusTestUtils.sys.mjs
index d36fccd170b3..7be889ae064f 100644
--- a/toolkit/components/nimbus/test/NimbusTestUtils.sys.mjs
+++ b/toolkit/components/nimbus/test/NimbusTestUtils.sys.mjs
@@ -12,7 +12,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
   ExperimentAPI: "resource://nimbus/ExperimentAPI.sys.mjs",
   FeatureManifest: "resource://nimbus/FeatureManifest.sys.mjs",
   JsonSchema: "resource://gre/modules/JsonSchema.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
   NormandyUtils: "resource://normandy/lib/NormandyUtils.sys.mjs",
   _ExperimentManager: "resource://nimbus/lib/ExperimentManager.sys.mjs",
@@ -21,6 +20,10 @@ ChromeUtils.defineESModuleGetters(lazy, {
   sinon: "resource://testing-common/Sinon.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 function fetchSchemaSync(uri) {
   // Yes, this is doing a sync load, but this is only done *once* and we cache
   // the result after *and* it is test-only.
diff --git a/toolkit/components/pdfjs/content/PdfStreamConverter.sys.mjs b/toolkit/components/pdfjs/content/PdfStreamConverter.sys.mjs
index a2f78db0ce34..7f9eea1b45ed 100644
--- a/toolkit/components/pdfjs/content/PdfStreamConverter.sys.mjs
+++ b/toolkit/components/pdfjs/content/PdfStreamConverter.sys.mjs
@@ -27,13 +27,17 @@ import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
 const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   AsyncPrefs: "resource://gre/modules/AsyncPrefs.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   NetworkManager: "resource://pdf.js/PdfJsNetwork.sys.mjs",
   PdfJs: "resource://pdf.js/PdfJs.sys.mjs",
   PdfJsTelemetry: "resource://pdf.js/PdfJsTelemetry.sys.mjs",
   PdfSandbox: "resource://pdf.js/PdfSandbox.sys.mjs",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 var Svc = {};
 XPCOMUtils.defineLazyServiceGetter(
diff --git a/toolkit/components/places/BookmarkHTMLUtils.sys.mjs b/toolkit/components/places/BookmarkHTMLUtils.sys.mjs
index 87751bced8b4..ce9b7ee1de74 100644
--- a/toolkit/components/places/BookmarkHTMLUtils.sys.mjs
+++ b/toolkit/components/places/BookmarkHTMLUtils.sys.mjs
@@ -56,8 +56,7 @@
  * both require the content (= title) before actually creating it.
  */
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
-
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 import { FileUtils } from "resource://gre/modules/FileUtils.sys.mjs";
 import { PlacesUtils } from "resource://gre/modules/PlacesUtils.sys.mjs";
 
diff --git a/toolkit/components/places/Bookmarks.sys.mjs b/toolkit/components/places/Bookmarks.sys.mjs
index d49e88e45d14..59f69bef5354 100644
--- a/toolkit/components/places/Bookmarks.sys.mjs
+++ b/toolkit/components/places/Bookmarks.sys.mjs
@@ -57,8 +57,12 @@
 
 const lazy = {};
 
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesSyncUtils: "resource://gre/modules/PlacesSyncUtils.sys.mjs",
   PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
 });
diff --git a/toolkit/components/places/tests/head_common.js b/toolkit/components/places/tests/head_common.js
index 01e4dd8fe9a8..9ae5dd4e0ffc 100644
--- a/toolkit/components/places/tests/head_common.js
+++ b/toolkit/components/places/tests/head_common.js
@@ -34,7 +34,6 @@ ChromeUtils.defineESModuleGetters(this, {
   BookmarkHTMLUtils: "resource://gre/modules/BookmarkHTMLUtils.sys.mjs",
   BookmarkJSONUtils: "resource://gre/modules/BookmarkJSONUtils.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PlacesBackups: "resource://gre/modules/PlacesBackups.sys.mjs",
   PlacesDBUtils: "resource://gre/modules/PlacesDBUtils.sys.mjs",
   PlacesTestUtils: "resource://testing-common/PlacesTestUtils.sys.mjs",
@@ -47,6 +46,7 @@ ChromeUtils.defineESModuleGetters(this, {
 });
 
 XPCOMUtils.defineLazyModuleGetters(this, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   ObjectUtils: "resource://gre/modules/ObjectUtils.jsm",
 });
 
diff --git a/toolkit/components/reputationservice/test/unit/test_app_rep.js b/toolkit/components/reputationservice/test/unit/test_app_rep.js
index 9c381a7bebca..4bcbf4c0da9b 100644
--- a/toolkit/components/reputationservice/test/unit/test_app_rep.js
+++ b/toolkit/components/reputationservice/test/unit/test_app_rep.js
@@ -4,9 +4,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const gAppRep = Cc[
   "@mozilla.org/reputationservice/application-reputation-service;1"
diff --git a/toolkit/components/reputationservice/test/unit/test_app_rep_maclinux.js b/toolkit/components/reputationservice/test/unit/test_app_rep_maclinux.js
index a89197e8ec8f..352038376194 100644
--- a/toolkit/components/reputationservice/test/unit/test_app_rep_maclinux.js
+++ b/toolkit/components/reputationservice/test/unit/test_app_rep_maclinux.js
@@ -5,9 +5,11 @@
 
 // Globals
 
-ChromeUtils.defineESModuleGetters(this, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
-});
+ChromeUtils.defineModuleGetter(
+  this,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 const gAppRep = Cc[
   "@mozilla.org/reputationservice/application-reputation-service;1"
diff --git a/toolkit/components/reputationservice/test/unit/test_app_rep_windows.js b/toolkit/components/reputationservice/test/unit/test_app_rep_windows.js
index 597810859f7e..df09edcbea31 100644
--- a/toolkit/components/reputationservice/test/unit/test_app_rep_windows.js
+++ b/toolkit/components/reputationservice/test/unit/test_app_rep_windows.js
@@ -10,9 +10,13 @@
 
 // Globals
 
+ChromeUtils.defineModuleGetter(
+  this,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 ChromeUtils.defineESModuleGetters(this, {
   FileTestUtils: "resource://testing-common/FileTestUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
 
 const BackgroundFileSaverOutputStream = Components.Constructor(
diff --git a/toolkit/components/reputationservice/test/unit/test_login_rep.js b/toolkit/components/reputationservice/test/unit/test_login_rep.js
index d68dabc707ab..14f09189684c 100644
--- a/toolkit/components/reputationservice/test/unit/test_login_rep.js
+++ b/toolkit/components/reputationservice/test/unit/test_login_rep.js
@@ -4,9 +4,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // LoginReputationService
 const gLoginRep = Cc[
diff --git a/toolkit/components/search/tests/xpcshell/data/searchSuggestions.sjs b/toolkit/components/search/tests/xpcshell/data/searchSuggestions.sjs
index a227dbf24b44..85f51795b6d1 100644
--- a/toolkit/components/search/tests/xpcshell/data/searchSuggestions.sjs
+++ b/toolkit/components/search/tests/xpcshell/data/searchSuggestions.sjs
@@ -4,9 +4,7 @@
 let { setTimeout } = ChromeUtils.importESModule(
   "resource://gre/modules/Timer.sys.mjs"
 );
-let { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+let { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 Cu.importGlobalProperties(["TextEncoder"]);
 
diff --git a/toolkit/components/telemetry/tests/unit/head.js b/toolkit/components/telemetry/tests/unit/head.js
index c452765f468e..67d8a8b492e6 100644
--- a/toolkit/components/telemetry/tests/unit/head.js
+++ b/toolkit/components/telemetry/tests/unit/head.js
@@ -11,7 +11,6 @@ const { AppConstants } = ChromeUtils.importESModule(
 ChromeUtils.defineESModuleGetters(this, {
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
   Log: "resource://gre/modules/Log.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   Preferences: "resource://gre/modules/Preferences.sys.mjs",
   PromiseUtils: "resource://gre/modules/PromiseUtils.sys.mjs",
   TelemetryController: "resource://gre/modules/TelemetryController.sys.mjs",
@@ -24,6 +23,7 @@ ChromeUtils.defineESModuleGetters(this, {
 XPCOMUtils.defineLazyModuleGetters(this, {
   AddonTestUtils: "resource://testing-common/AddonTestUtils.jsm",
   HttpServer: "resource://testing-common/httpd.js",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 const gIsWindows = AppConstants.platform == "win";
diff --git a/toolkit/components/telemetry/tests/unit/test_CoveragePing.js b/toolkit/components/telemetry/tests/unit/test_CoveragePing.js
index 89842623e301..7fd7da0baa3b 100644
--- a/toolkit/components/telemetry/tests/unit/test_CoveragePing.js
+++ b/toolkit/components/telemetry/tests/unit/test_CoveragePing.js
@@ -2,9 +2,7 @@
 /* vim: set sts=2 sw=2 et tw=80: */
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
 
diff --git a/toolkit/components/thumbnails/test/test_thumbnails_interfaces.js b/toolkit/components/thumbnails/test/test_thumbnails_interfaces.js
index eb70e8011b1e..394b8591a864 100644
--- a/toolkit/components/thumbnails/test/test_thumbnails_interfaces.js
+++ b/toolkit/components/thumbnails/test/test_thumbnails_interfaces.js
@@ -3,9 +3,7 @@
 // This is an xpcshell test and gets a browser test env applied, so we
 // need to still manually import NetUtil.
 // eslint-disable-next-line mozilla/no-redeclare-with-import-autofix
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 // need profile so that PageThumbsStorageService can resolve the path to the underlying file
 do_get_profile();
diff --git a/toolkit/components/url-classifier/UrlClassifierHashCompleter.sys.mjs b/toolkit/components/url-classifier/UrlClassifierHashCompleter.sys.mjs
index 48a4c432fb0a..521b33dca32b 100644
--- a/toolkit/components/url-classifier/UrlClassifierHashCompleter.sys.mjs
+++ b/toolkit/components/url-classifier/UrlClassifierHashCompleter.sys.mjs
@@ -14,7 +14,7 @@ const PREF_DEBUG_ENABLED = "browser.safebrowsing.debug";
 
 import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 const lazy = {};
 
diff --git a/toolkit/components/url-classifier/tests/unit/head_urlclassifier.js b/toolkit/components/url-classifier/tests/unit/head_urlclassifier.js
index 97b0410928c5..840dc8d5581f 100644
--- a/toolkit/components/url-classifier/tests/unit/head_urlclassifier.js
+++ b/toolkit/components/url-classifier/tests/unit/head_urlclassifier.js
@@ -377,9 +377,11 @@ function updateError(arg) {
 /**
  * Utility functions
  */
-ChromeUtils.defineESModuleGetters(this, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
-});
+ChromeUtils.defineModuleGetter(
+  this,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 function readFileToString(aFilename) {
   let f = do_get_file(aFilename);
diff --git a/toolkit/components/url-classifier/tests/unit/test_channelClassifierService.js b/toolkit/components/url-classifier/tests/unit/test_channelClassifierService.js
index 9d5f5edb65ec..f7a100cc0ea2 100644
--- a/toolkit/components/url-classifier/tests/unit/test_channelClassifierService.js
+++ b/toolkit/components/url-classifier/tests/unit/test_channelClassifierService.js
@@ -8,9 +8,7 @@
 
 var httpserver = new HttpServer();
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { UrlClassifierTestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/UrlClassifierTestUtils.sys.mjs"
 );
diff --git a/toolkit/components/url-classifier/tests/unit/test_shouldclassify.js b/toolkit/components/url-classifier/tests/unit/test_shouldclassify.js
index 6abdbb5f8587..3d56adb8936b 100644
--- a/toolkit/components/url-classifier/tests/unit/test_shouldclassify.js
+++ b/toolkit/components/url-classifier/tests/unit/test_shouldclassify.js
@@ -4,9 +4,7 @@
 
 "use strict";
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { UrlClassifierTestUtils } = ChromeUtils.importESModule(
   "resource://testing-common/UrlClassifierTestUtils.sys.mjs"
 );
diff --git a/toolkit/components/utils/SimpleServices.sys.mjs b/toolkit/components/utils/SimpleServices.sys.mjs
index 55200e95b519..bfd81724f656 100644
--- a/toolkit/components/utils/SimpleServices.sys.mjs
+++ b/toolkit/components/utils/SimpleServices.sys.mjs
@@ -16,9 +16,11 @@ import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
 
 const lazy = {};
 
-ChromeUtils.defineESModuleGetters(lazy, {
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
-});
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 XPCOMUtils.defineLazyServiceGetter(
   lazy,
diff --git a/toolkit/content/contentAreaUtils.js b/toolkit/content/contentAreaUtils.js
index 93b43c46fa1c..c66c92991b36 100644
--- a/toolkit/content/contentAreaUtils.js
+++ b/toolkit/content/contentAreaUtils.js
@@ -16,10 +16,13 @@ ChromeUtils.defineESModuleGetters(this, {
   DownloadPaths: "resource://gre/modules/DownloadPaths.sys.mjs",
   Downloads: "resource://gre/modules/Downloads.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
 });
 
+XPCOMUtils.defineLazyModuleGetters(this, {
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
+});
+
 var ContentAreaUtils = {
   get stringBundle() {
     delete this.stringBundle;
diff --git a/toolkit/modules/JSONFile.sys.mjs b/toolkit/modules/JSONFile.sys.mjs
index 053f5cbd447e..fde0ec5e8b0a 100644
--- a/toolkit/modules/JSONFile.sys.mjs
+++ b/toolkit/modules/JSONFile.sys.mjs
@@ -35,8 +35,12 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   DeferredTask: "resource://gre/modules/DeferredTask.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
 });
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "NetUtil",
+  "resource://gre/modules/NetUtil.jsm"
+);
 
 XPCOMUtils.defineLazyGetter(lazy, "gTextDecoder", function () {
   return new TextDecoder();
diff --git a/toolkit/modules/tests/modules/MockDocument.sys.mjs b/toolkit/modules/tests/modules/MockDocument.sys.mjs
index 163beb84503f..efcb6360ba56 100644
--- a/toolkit/modules/tests/modules/MockDocument.sys.mjs
+++ b/toolkit/modules/tests/modules/MockDocument.sys.mjs
@@ -2,7 +2,7 @@
  * Provides infrastructure for tests that would require mock document.
  */
 
-import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 export const MockDocument = {
   /**
diff --git a/toolkit/mozapps/extensions/internal/AddonRepository.jsm b/toolkit/mozapps/extensions/internal/AddonRepository.jsm
index 265d98e1282c..58462c8c7a13 100644
--- a/toolkit/mozapps/extensions/internal/AddonRepository.jsm
+++ b/toolkit/mozapps/extensions/internal/AddonRepository.jsm
@@ -13,7 +13,6 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   AsyncShutdown: "resource://gre/modules/AsyncShutdown.sys.mjs",
   DeferredTask: "resource://gre/modules/DeferredTask.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   Preferences: "resource://gre/modules/Preferences.sys.mjs",
   ServiceRequest: "resource://gre/modules/ServiceRequest.sys.mjs",
 });
@@ -21,6 +20,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
 XPCOMUtils.defineLazyModuleGetters(lazy, {
   AddonManager: "resource://gre/modules/AddonManager.jsm",
   AddonManagerPrivate: "resource://gre/modules/AddonManager.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
 });
 
 // The current platform as specified in the AMO API:
diff --git a/toolkit/mozapps/extensions/internal/AddonTestUtils.jsm b/toolkit/mozapps/extensions/internal/AddonTestUtils.jsm
index c259695bc9e3..a4f39108eb1d 100644
--- a/toolkit/mozapps/extensions/internal/AddonTestUtils.jsm
+++ b/toolkit/mozapps/extensions/internal/AddonTestUtils.jsm
@@ -20,9 +20,7 @@ const { AsyncShutdown } = ChromeUtils.importESModule(
 const { FileUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/FileUtils.sys.mjs"
 );
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/toolkit/mozapps/extensions/internal/XPIInstall.jsm b/toolkit/mozapps/extensions/internal/XPIInstall.jsm
index d07b875eb3dc..a4073da7bd23 100644
--- a/toolkit/mozapps/extensions/internal/XPIInstall.jsm
+++ b/toolkit/mozapps/extensions/internal/XPIInstall.jsm
@@ -43,7 +43,6 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
   CertUtils: "resource://gre/modules/CertUtils.sys.mjs",
   FileUtils: "resource://gre/modules/FileUtils.sys.mjs",
-  NetUtil: "resource://gre/modules/NetUtil.sys.mjs",
   UpdateUtils: "resource://gre/modules/UpdateUtils.sys.mjs",
 });
 
@@ -52,6 +51,7 @@ XPCOMUtils.defineLazyModuleGetters(lazy, {
   AddonSettings: "resource://gre/modules/addons/AddonSettings.jsm",
   BuiltInThemesHelpers: "resource://gre/modules/addons/XPIDatabase.jsm",
   ExtensionData: "resource://gre/modules/Extension.jsm",
+  NetUtil: "resource://gre/modules/NetUtil.jsm",
   ProductAddonChecker: "resource://gre/modules/addons/ProductAddonChecker.jsm",
   AddonInternal: "resource://gre/modules/addons/XPIDatabase.jsm",
   XPIDatabase: "resource://gre/modules/addons/XPIDatabase.jsm",
diff --git a/toolkit/mozapps/extensions/test/xpcshell/head_addons.js b/toolkit/mozapps/extensions/test/xpcshell/head_addons.js
index 121949d98d71..b54534d21740 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/head_addons.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/head_addons.js
@@ -39,9 +39,7 @@ var { AppConstants } = ChromeUtils.importESModule(
 var { FileUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/FileUtils.sys.mjs"
 );
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/toolkit/mozapps/extensions/test/xpinstall/slowinstall.sjs b/toolkit/mozapps/extensions/test/xpinstall/slowinstall.sjs
index 3251cd3ad922..c925822a4dd4 100644
--- a/toolkit/mozapps/extensions/test/xpinstall/slowinstall.sjs
+++ b/toolkit/mozapps/extensions/test/xpinstall/slowinstall.sjs
@@ -1,9 +1,7 @@
 // In an SJS file we need to get NetUtil ourselves, despite
 // what eslint might think applies for browser tests.
 // eslint-disable-next-line mozilla/no-redeclare-with-import-autofix
-let { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+let { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 Cu.importGlobalProperties(["IOUtils", "PathUtils"]);
 
diff --git a/toolkit/profile/xpcshell/head.js b/toolkit/profile/xpcshell/head.js
index fd469db3ae3f..9c41a3607899 100644
--- a/toolkit/profile/xpcshell/head.js
+++ b/toolkit/profile/xpcshell/head.js
@@ -1,9 +1,7 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 const { FileUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/FileUtils.sys.mjs"
 );
diff --git a/uriloader/exthandler/tests/unit/head.js b/uriloader/exthandler/tests/unit/head.js
index 72d1ac87c50c..2f65582ae929 100644
--- a/uriloader/exthandler/tests/unit/head.js
+++ b/uriloader/exthandler/tests/unit/head.js
@@ -14,9 +14,7 @@ var { AppConstants } = ChromeUtils.importESModule(
 var { FileUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/FileUtils.sys.mjs"
 );
-var { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 var { XPCOMUtils } = ChromeUtils.importESModule(
   "resource://gre/modules/XPCOMUtils.sys.mjs"
 );
diff --git a/xpcom/tests/unit/test_bug121341.js b/xpcom/tests/unit/test_bug121341.js
index 2e66970092d5..2796fc47f206 100644
--- a/xpcom/tests/unit/test_bug121341.js
+++ b/xpcom/tests/unit/test_bug121341.js
@@ -1,6 +1,4 @@
-const { NetUtil } = ChromeUtils.importESModule(
-  "resource://gre/modules/NetUtil.sys.mjs"
-);
+const { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm");
 
 function run_test() {
   var dataFile = do_get_file("data/bug121341.properties");