diff --git a/browser/base/content/test/permissions/head.js b/browser/base/content/test/permissions/head.js
index 3b93186080f6..962f15bc4c4d 100644
--- a/browser/base/content/test/permissions/head.js
+++ b/browser/base/content/test/permissions/head.js
@@ -4,7 +4,7 @@ const { PermissionTestUtils } = ChromeUtils.import(
 
 SpecialPowers.addTaskImport(
   "E10SUtils",
-  "resource://gre/modules/E10SUtils.jsm"
+  "resource://gre/modules/E10SUtils.sys.mjs"
 );
 
 function openPermissionPopup() {
diff --git a/testing/specialpowers/content/SpecialPowersChild.sys.mjs b/testing/specialpowers/content/SpecialPowersChild.sys.mjs
index 0449c1094c9f..79933804605f 100644
--- a/testing/specialpowers/content/SpecialPowersChild.sys.mjs
+++ b/testing/specialpowers/content/SpecialPowersChild.sys.mjs
@@ -1649,7 +1649,7 @@ export class SpecialPowersChild extends JSWindowActorChild {
   }
 
   /**
-   * Automatically imports the given symbol from the given JSM for any
+   * Automatically imports the given symbol from the given sys.mjs for any
    * task spawned by this SpecialPowers instance.
    */
   addTaskImport(symbol, url) {
diff --git a/testing/specialpowers/content/SpecialPowersSandbox.sys.mjs b/testing/specialpowers/content/SpecialPowersSandbox.sys.mjs
index cbeb02a237c3..1ad127636418 100644
--- a/testing/specialpowers/content/SpecialPowersSandbox.sys.mjs
+++ b/testing/specialpowers/content/SpecialPowersSandbox.sys.mjs
@@ -28,7 +28,7 @@ const SANDBOX_GLOBALS = [
   "URL",
 ];
 const EXTRA_IMPORTS = {
-  EventUtils: "resource://specialpowers/SpecialPowersEventUtils.jsm",
+  EventUtils: "resource://specialpowers/SpecialPowersEventUtils.sys.mjs",
 };
 
 let expectFail = false;
@@ -70,9 +70,10 @@ export class SpecialPowersSandbox {
       ...EXTRA_IMPORTS,
       ...opts.imports,
     };
-    for (let [symbol, url] of Object.entries(imports)) {
-      ChromeUtils.defineModuleGetter(this.sandbox, symbol, url);
-    }
+    // We explicitly want these directly in the sandbox, and we aren't going
+    // to be using the globals within this file.
+    // eslint-disable-next-line mozilla/lazy-getter-object-name
+    ChromeUtils.defineESModuleGetters(this.sandbox, imports);
 
     // Note: When updating the set of globals exposed to sandboxes by
     // default, please also update the ESLint plugin rule defined in
diff --git a/toolkit/components/narrate/test/head.js b/toolkit/components/narrate/test/head.js
index 9eb95085d555..a69a9039fc0c 100644
--- a/toolkit/components/narrate/test/head.js
+++ b/toolkit/components/narrate/test/head.js
@@ -65,7 +65,7 @@ function spawnInNewReaderTab(url, func) {
       SpecialPowers.addTaskImport(
         "NarrateTestUtils",
         "chrome://mochitests/content/browser/" +
-          "toolkit/components/narrate/test/NarrateTestUtils.jsm"
+          "toolkit/components/narrate/test/NarrateTestUtils.sys.mjs"
       );
       await SpecialPowers.spawn(browser, [], async function() {
         await NarrateTestUtils.getReaderReadyPromise(content);