--- a/browser/components/extensions/test/browser/browser_ext_menus_events.js
+++ b/browser/components/extensions/test/browser/browser_ext_menus_events.js
@@ -389,16 +389,18 @@ add_task(async function test_show_hide_f
       contexts: ["frame", "all"],
       editable: false,
       get frameId() { return frameId; },
       pageUrl: PAGE,
       frameUrl: PAGE_BASE + "context_frame.html",
     },
     async doOpenMenu() {
       frameId = await ContentTask.spawn(gBrowser.selectedBrowser, {}, function() {
+        ChromeUtils.import("resource://gre/modules/WebNavigationFrames.jsm");
+
         let {contentWindow} = content.document.getElementById("frame");
         return WebNavigationFrames.getFrameId(contentWindow);
       });
       await openContextMenuInFrame("#frame");
     },
     async doCloseMenu() {
       await closeExtensionContextMenu();
     },