diff --git a/dom/localstorage/moz.build b/dom/localstorage/moz.build
index 9a9228c8b28b..00c9a96e6681 100644
--- a/dom/localstorage/moz.build
+++ b/dom/localstorage/moz.build
@@ -17,7 +17,7 @@ TEST_HARNESS_FILES.xpcshell.dom.localstorage.test.unit += [
     "test/unit/databaseShadowing-shared.js",
 ]
 
-TEST_DIRS += ["test/gtest"]
+TEST_DIRS += ["test"]
 
 XPIDL_SOURCES += [
     "nsILocalStorageManager.idl",
diff --git a/dom/localstorage/test/modules/system/LocalStorageUtils.sys.mjs b/dom/localstorage/test/modules/system/LocalStorageUtils.sys.mjs
new file mode 100644
index 000000000000..8fb20872aee2
--- /dev/null
+++ b/dom/localstorage/test/modules/system/LocalStorageUtils.sys.mjs
@@ -0,0 +1,15 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+export const LocalStorageUtils = {
+  createStorage(principal) {
+    return Services.domStorageManager.createStorage(
+      null,
+      principal,
+      principal,
+      ""
+    );
+  },
+};
diff --git a/dom/localstorage/test/moz.build b/dom/localstorage/test/moz.build
new file mode 100644
index 000000000000..89d10993d9e0
--- /dev/null
+++ b/dom/localstorage/test/moz.build
@@ -0,0 +1,11 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+TEST_DIRS += ["gtest"]
+
+TESTING_JS_MODULES.dom.localstorage.test.modules += [
+    "modules/system/LocalStorageUtils.sys.mjs",
+]