diff --git a/dom/media/test/can_play_type_webm.js b/dom/media/test/can_play_type_webm.js
index 7c8b42f10729..75b6c1e7c2c1 100644
--- a/dom/media/test/can_play_type_webm.js
+++ b/dom/media/test/can_play_type_webm.js
@@ -35,15 +35,6 @@ async function check_webm(v, enabled) {
     return pref;
   }
 
-  function isWindows32() {
-    return navigator.userAgent.includes("Windows") &&
-           !navigator.userAgent.includes("Win64");
-  }
-
-  function isAndroid() {
-    return navigator.userAgent.includes("Android");
-  }
-
   await SpecialPowers.pushPrefEnv({"set": [["media.av1.enabled", true]]});
   // AV1 is disabled on Windows 32 bits (bug 1475564) and Android (bug 1368843)
   check("video/webm; codecs=\"av1\"", (isWindows32() || isAndroid()) ? "" : "probably");
diff --git a/dom/media/test/manifest.js b/dom/media/test/manifest.js
index 88b5a4d0feec..8a9d9d5b8494 100644
--- a/dom/media/test/manifest.js
+++ b/dom/media/test/manifest.js
@@ -633,6 +633,15 @@ var gUnseekableTests = [
   { name:"bogus.duh", type:"bogus/duh"}
 ];
 
+function isWindows32() {
+    return navigator.userAgent.includes("Windows") &&
+        !navigator.userAgent.includes("Win64");
+}
+
+function isAndroid() {
+    return navigator.userAgent.includes("Android");
+}
+
 var androidVersion = -1; // non-Android platforms
 if (manifestNavigator().userAgent.includes("Mobile") ||
     manifestNavigator().userAgent.includes("Tablet")) {
diff --git a/dom/media/test/test_can_play_type_mpeg.html b/dom/media/test/test_can_play_type_mpeg.html
index 37a9526566be..1a5d4f2551ce 100644
--- a/dom/media/test/test_can_play_type_mpeg.html
+++ b/dom/media/test/test_can_play_type_mpeg.html
@@ -98,8 +98,7 @@ function check_mp4(v, enabled) {
   });
   // AV1 is temporarily disabled on Win32 due to linker issues
   // https://bugzilla.mozilla.org/show_bug.cgi?id=1475564
-  if (!(manifestNavigator().userAgent.includes("Windows") &&
-      !manifestNavigator().userAgent.includes("x64"))) {
+  if (!isWindows32() && !isAndroid()) {
     check("video/mp4; codecs=\"av1\"", "probably");
   } else {
     check("video/mp4; codecs=\"av1\"", "");