diff --git a/browser/modules/BackgroundTask_install.sys.mjs b/browser/modules/BackgroundTask_install.sys.mjs
index 510e14bccb90..8aed98a071ad 100644
--- a/browser/modules/BackgroundTask_install.sys.mjs
+++ b/browser/modules/BackgroundTask_install.sys.mjs
@@ -20,7 +20,7 @@ export async function runBackgroundTask() {
 
   console.log("Cleaning up update files.");
   try {
-    Cc["@mozilla.org/updates/update-manager;1"]
+    await Cc["@mozilla.org/updates/update-manager;1"]
       .getService(Ci.nsIUpdateManager)
       .doInstallCleanup();
   } catch (ex) {
diff --git a/browser/modules/BackgroundTask_uninstall.sys.mjs b/browser/modules/BackgroundTask_uninstall.sys.mjs
index f2fc9a0f8c13..c19bbe98d93d 100644
--- a/browser/modules/BackgroundTask_uninstall.sys.mjs
+++ b/browser/modules/BackgroundTask_uninstall.sys.mjs
@@ -27,7 +27,7 @@ export async function runBackgroundTask() {
 
   console.log("Cleaning up update files.");
   try {
-    Cc["@mozilla.org/updates/update-manager;1"]
+    await Cc["@mozilla.org/updates/update-manager;1"]
       .getService(Ci.nsIUpdateManager)
       .doUninstallCleanup();
   } catch (ex) {