diff --git a/browser/actors/PageStyleChild.jsm b/browser/actors/PageStyleChild.sys.mjs
similarity index 98%
rename from browser/actors/PageStyleChild.jsm
rename to browser/actors/PageStyleChild.sys.mjs
index 686b67c4321d..7bf9774c515e 100644
--- a/browser/actors/PageStyleChild.jsm
+++ b/browser/actors/PageStyleChild.sys.mjs
@@ -1,11 +1,8 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * 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/. */
-"use strict";
 
-var EXPORTED_SYMBOLS = ["PageStyleChild"];
-
-class PageStyleChild extends JSWindowActorChild {
+export class PageStyleChild extends JSWindowActorChild {
   actorCreated() {
     // C++ can create the actor and call us here once an "interesting" link
     // element gets added to the DOM. If pageload hasn't finished yet, just
diff --git a/browser/actors/PageStyleParent.jsm b/browser/actors/PageStyleParent.sys.mjs
similarity index 95%
rename from browser/actors/PageStyleParent.jsm
rename to browser/actors/PageStyleParent.sys.mjs
index 8d3b57b52c8f..426a886ad4a4 100644
--- a/browser/actors/PageStyleParent.jsm
+++ b/browser/actors/PageStyleParent.sys.mjs
@@ -1,11 +1,8 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * 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/. */
-"use strict";
 
-var EXPORTED_SYMBOLS = ["PageStyleParent"];
-
-class PageStyleParent extends JSWindowActorParent {
+export class PageStyleParent extends JSWindowActorParent {
   // This has the most recent information about the content stylesheets for
   // that actor. It's populated via the PageStyle:Add and PageStyle:Clear
   // messages from the content process. It has the following structure:
diff --git a/browser/actors/moz.build b/browser/actors/moz.build
index dd28df34f453..31ca09aff5e6 100644
--- a/browser/actors/moz.build
+++ b/browser/actors/moz.build
@@ -19,7 +19,7 @@ with Files("LightweightThemeChild.jsm"):
 with Files("PageInfoChild.sys.mjs"):
     BUG_COMPONENT = ("Firefox", "Page Info Window")
 
-with Files("PageStyleChild.jsm"):
+with Files("PageStyleChild.sys.mjs"):
     BUG_COMPONENT = ("Firefox", "Menus")
 
 with Files("PluginChild.jsm"):
@@ -68,8 +68,8 @@ FINAL_TARGET_FILES.actors += [
     "LinkHandlerChild.jsm",
     "LinkHandlerParent.jsm",
     "PageInfoChild.sys.mjs",
-    "PageStyleChild.jsm",
-    "PageStyleParent.jsm",
+    "PageStyleChild.sys.mjs",
+    "PageStyleParent.sys.mjs",
     "PluginChild.jsm",
     "PluginParent.jsm",
     "PointerLockChild.sys.mjs",
diff --git a/browser/components/BrowserGlue.sys.mjs b/browser/components/BrowserGlue.sys.mjs
index 640c7a5e6577..a73070ea80c9 100644
--- a/browser/components/BrowserGlue.sys.mjs
+++ b/browser/components/BrowserGlue.sys.mjs
@@ -632,10 +632,10 @@ let JSWINDOWACTORS = {
 
   PageStyle: {
     parent: {
-      moduleURI: "resource:///actors/PageStyleParent.jsm",
+      esModuleURI: "resource:///actors/PageStyleParent.sys.mjs",
     },
     child: {
-      moduleURI: "resource:///actors/PageStyleChild.jsm",
+      esModuleURI: "resource:///actors/PageStyleChild.sys.mjs",
       events: {
         pageshow: { createActor: false },
       },
diff --git a/docshell/base/BrowsingContext.cpp b/docshell/base/BrowsingContext.cpp
index 5008bdc0cbf3..1191a7062da3 100644
--- a/docshell/base/BrowsingContext.cpp
+++ b/docshell/base/BrowsingContext.cpp
@@ -3281,7 +3281,7 @@ void BrowsingContext::DidSet(FieldIndex<IDX_AuthorStyleDisabledDefault>) {
              "Should only set AuthorStyleDisabledDefault in the top "
              "browsing context");
 
-  // We don't need to handle changes to this field, since PageStyleChild.jsm
+  // We don't need to handle changes to this field, since PageStyleChild.sys.mjs
   // will respond to the PageStyle:Disable message in all content processes.
   //
   // But we store the state here on the top BrowsingContext so that the
diff --git a/dom/base/Document.cpp b/dom/base/Document.cpp
index 1023d3caa9d1..c2d38b9c694c 100644
--- a/dom/base/Document.cpp
+++ b/dom/base/Document.cpp
@@ -6856,7 +6856,7 @@ already_AddRefed<PresShell> Document::CreatePresShell(
   MarkUserFontSetDirty();
 
   // Take the author style disabled state from the top browsing cvontext.
-  // (PageStyleChild.jsm ensures this is up to date.)
+  // (PageStyleChild.sys.mjs ensures this is up to date.)
   if (BrowsingContext* bc = GetBrowsingContext()) {
     presShell->SetAuthorStyleDisabled(bc->Top()->AuthorStyleDisabledDefault());
   }