diff --git a/toolkit/content/tests/widgets/mochitest.ini b/toolkit/content/tests/widgets/mochitest.ini
index a78cbac92788..8aa19df966e7 100644
--- a/toolkit/content/tests/widgets/mochitest.ini
+++ b/toolkit/content/tests/widgets/mochitest.ini
@@ -25,6 +25,7 @@ support-files =
   videomask.css
 
 [test_audiocontrols_dimensions.html]
+[test_audiocontrols_fullscreen.html]
 [test_mousecapture_area.html]
 [test_ua_widget_sandbox.html]
 [test_ua_widget_unbind.html]
diff --git a/toolkit/content/tests/widgets/test_audiocontrols_fullscreen.html b/toolkit/content/tests/widgets/test_audiocontrols_fullscreen.html
new file mode 100644
index 000000000000..6963c3da1e23
--- /dev/null
+++ b/toolkit/content/tests/widgets/test_audiocontrols_fullscreen.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Audio controls test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+
+<div id="content">
+  <audio id="audio" controls preload="auto"></audio>
+</div>
+
+<pre id="test">
+<script class="testbody" type="text/javascript">
+  const audio = document.getElementById("audio");
+  const controlBar = getElementWithinVideo(audio, "controlBar");
+
+  add_setup(async function setup() {
+    await new Promise(resolve => {
+      audio.addEventListener("loadedmetadata", resolve, {once: true});
+      audio.src = "audio.wav";
+    });
+  });
+
+  add_task(async function test_double_click_does_not_fullscreen() {
+    SimpleTest.requestCompleteLog();
+    SimpleTest.requestFlakyTimeout("Waiting to ensure that fullscreen event does not fire");
+    const { x, y } = audio.getBoundingClientRect();
+    const endedPromise = new Promise(resolve => {
+      audio.addEventListener("ended", () => {
+        info('Audio ended event fired!');
+        resolve();
+      }, { once: true });
+      setTimeout( () => {
+        info('Audio ran out of time before ended event fired!');
+        resolve();
+      }, audio.duration * 1000);
+    });
+    let noFullscreenEvent = true;
+    document.addEventListener("mozfullscreenchange", () => {
+      noFullscreenEvent = false;
+    }, { once: true });
+    info("Simulate double click on media player.");
+    synthesizeMouse(audio, x, y, { clickCount: 2 });
+    info("Waiting for video to end...");
+    await endedPromise;
+    // By this point, if the double click was going to trigger fullscreen then
+    // it should have happened by now.
+    ok(
+      noFullscreenEvent,
+      "Double clicking should not trigger fullscreen event"
+    );
+  });
+</script>
+</pre>
+</body>
+</html>
diff --git a/toolkit/content/tests/widgets/test_videocontrols_audio.html b/toolkit/content/tests/widgets/test_videocontrols_audio.html
index d953e4ae74e4..491c59717493 100644
--- a/toolkit/content/tests/widgets/test_videocontrols_audio.html
+++ b/toolkit/content/tests/widgets/test_videocontrols_audio.html
@@ -29,7 +29,7 @@
     let children =
       InspectorUtils.getChildrenForNode(element, true);
     for (let child of children) {
-      var result = findElementByAttribute(child, aName, aValue);
+      const result = findElementByAttribute(child, aName, aValue);
       if (result) {
         return result;
       }
@@ -38,36 +38,9 @@
   }
 
   function loadedmetadata(event) {
-    SimpleTest.requestCompleteLog();
-    SimpleTest.executeSoon(async function test_fullscreen_unavailable() {
-      const { x, y } = video.getBoundingClientRect();
+    SimpleTest.executeSoon(function() {
       const controlBar = findElementByAttribute(video, "class", "controlBar");
-      SimpleTest.requestFlakyTimeout("Waiting to ensure that fullscreen event does not fire");
-      const endedPromise = new Promise(resolve => {
-        video.addEventListener("ended", () => {
-          info('Video ended event fired!');
-          resolve();
-        }, { once: true });
-        setTimeout( () => {
-          info('Video ran out of time before ended event fired!');
-          resolve();
-        }, video.duration * 1000);
-      });
-      let noFullscreenEvent = true;
       is(controlBar.getAttribute("fullscreen-unavailable"), "true", "Fullscreen button is hidden");
-      document.addEventListener("mozfullscreenchange", () => {
-        noFullscreenEvent = false;
-      }, { once: true });
-      info("Simulate double click on media player.");
-      synthesizeMouse(video, x, y, { clickCount: 2 });
-      info("Waiting for video to end...");
-      await endedPromise;
-      // By this point, if the double click was going to trigger fullscreen then
-      // it should have happened by now.
-      ok(
-        noFullscreenEvent,
-        "Double clicking should not trigger fullscreen event"
-      );
       SimpleTest.finish();
     });
   }
diff --git a/toolkit/content/widgets/videocontrols.js b/toolkit/content/widgets/videocontrols.js
index 9bbce74249c4..547929027f21 100644
--- a/toolkit/content/widgets/videocontrols.js
+++ b/toolkit/content/widgets/videocontrols.js
@@ -299,6 +299,10 @@ this.VideoControlsImplWidget = class {
       isPausedByDragging: false,
       _isAudioOnly: false,
 
+      get isAudioTag() {
+        return this.video.localName == "audio";
+      },
+
       get isAudioOnly() {
         return this._isAudioOnly;
       },
@@ -788,7 +792,7 @@ this.VideoControlsImplWidget = class {
             this.controlsSpacer.removeAttribute("aria-label");
             this.statusOverlay.removeAttribute("status");
             this.statusIcon.setAttribute("type", "throbber");
-            this.isAudioOnly = this.video.localName == "audio";
+            this.isAudioOnly = this.isAudioTag;
             this.setPlayButtonState(true);
             this.setupNewLoadState();
             this.setupStatusFader();
@@ -1706,7 +1710,7 @@ this.VideoControlsImplWidget = class {
 
       toggleFullscreen() {
         // audio tags cannot toggle fullscreen
-        if (!this.isAudioOnly) {
+        if (!this.isAudioTag) {
           this.isVideoInFullScreen
             ? this.document.exitFullscreen()
             : this.video.requestFullscreen();
@@ -2436,7 +2440,7 @@ this.VideoControlsImplWidget = class {
 
         // Since the size of videocontrols is expanded with controlBar in <audio>, we
         // should fix the dimensions in order not to recursively trigger reflow afterwards.
-        if (this.video.localName == "audio") {
+        if (this.isAudioTag) {
           if (givenHeight) {
             // The height of controlBar should be capped with the bounds between controlBarMinHeight
             // and controlBarMinVisibleHeight.
@@ -2596,7 +2600,7 @@ this.VideoControlsImplWidget = class {
           this.volumeStack,
         ];
 
-        this.isAudioOnly = this.video.localName == "audio";
+        this.isAudioOnly = this.isAudioTag;
         this.setupInitialState();
         this.setupNewLoadState();
         this.initTextTracks();
