--- a/toolkit/components/extensions/test/mochitest/test_ext_redirect_jar.html
+++ b/toolkit/components/extensions/test/mochitest/test_ext_redirect_jar.html
@@ -54,17 +54,16 @@ function getExtension() {
       async function testSubFrameResource(tabId, code) {
         let [result] = await browser.tabs.executeScript(tabId, {code: `
           new Promise(resolve => {
             var s = document.createElement('iframe');
             s.src = "/intercept?r=" + Math.random();
             s.onload = () => resolve(['loaded', s.contentWindow.location.href]);
             s.onerror = () => resolve(['error']);
             document.documentElement.appendChild(s);
-            setTimeout(() => resolve(['timed_out']), 5000);
           });`,
         });
         return result;
       }
 
       let tab = await browser.tabs.create({url: "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_sample.html"});
       let result = await testSubFrameResource(tab.id);
       browser.test.assertEq("loaded", result[0], "frame 1 loaded");