diff --git a/browser/components/originattributes/test/browser/browser_cache.js b/browser/components/originattributes/test/browser/browser_cache.js
index 01668b16bc4b..01354cc71301 100644
--- a/browser/components/originattributes/test/browser/browser_cache.js
+++ b/browser/components/originattributes/test/browser/browser_cache.js
@@ -184,6 +184,7 @@ async function doTest(aBrowser) {
       audioSource.setAttribute("type", "audio/ogg");
       audioTrack.setAttribute("src", trackURL);
       audioTrack.setAttribute("kind", "subtitles");
+      audioTrack.setAttribute("default", true);
 
       audio.appendChild(audioSource);
       audio.appendChild(audioTrack);
diff --git a/toolkit/components/url-classifier/tests/mochitest/test_classify_track.html b/toolkit/components/url-classifier/tests/mochitest/test_classify_track.html
index 3c3ee6e1abef..598d260dbfd2 100644
--- a/toolkit/components/url-classifier/tests/mochitest/test_classify_track.html
+++ b/toolkit/components/url-classifier/tests/mochitest/test_classify_track.html
@@ -30,6 +30,7 @@
 
     return new Promise(function(resolve, reject) {
       var track = document.createElement("track");
+      track.track.mode = "hidden";
       track.src = validtrack_url;
       video.appendChild(track);
 
@@ -59,6 +60,7 @@
 
     return new Promise(function(resolve, reject) {
       var track = document.createElement("track");
+      track.track.mode = "hidden";
       track.src = malware_url;
       video.appendChild(track);
 
@@ -88,7 +90,7 @@
 
     return new Promise(function(resolve, reject) {
       var track = document.createElement("track");
-
+      track.track.mode = "hidden";
       // Add a query string parameter here to avoid url classifier bypass classify
       // because of cache.
       track.src = malware_url + "?testsbon";
diff --git a/toolkit/components/url-classifier/tests/mochitest/trackerFrame.html b/toolkit/components/url-classifier/tests/mochitest/trackerFrame.html
index 622dd0c79f71..9d89edde80dc 100644
--- a/toolkit/components/url-classifier/tests/mochitest/trackerFrame.html
+++ b/toolkit/components/url-classifier/tests/mochitest/trackerFrame.html
@@ -30,7 +30,7 @@
 </video>
 
 <video src="http://mochi.test:8888/basic.vtt", crossorigin=use-credentials>
-  <track src="http://itisatracker.org/tests/toolkit/components/url-classifier/tests/mochitest/trackerFrame.sjs?id=track-src" ></track>
+  <track default src="http://itisatracker.org/tests/toolkit/components/url-classifier/tests/mochitest/trackerFrame.sjs?id=track-src" ></track>
 </video>
 
 <!--SendPing-->