--- a/dom/media/test/test_decode_error.html
+++ b/dom/media/test/test_decode_error.html
@@ -22,16 +22,18 @@ function startTest(test, token) {
   var v = document.createElement("video");
   manager.started(token);
   v.addEventListener("error", function (event) {
     var el = event.currentTarget;
     is(event.type, "error", "Expected event of type 'error'");
     ok(el.error, "Element 'error' attr expected to have a value");
     ok(el.error instanceof MediaError, "Element 'error' attr expected to be MediaError");
     is(el.error.code, MediaError.MEDIA_ERR_DECODE, "Expected a decode error");
+    ok(typeof el.error.message === 'string' || el.error.essage instanceof String, "Element 'message' attr expected to be a string");
+    ok(el.error.message.length > 0, "Element 'message' attr has content");
     el._sawError = true;
     manager.finished(token);
   }, false);
 
   v.addEventListener("loadeddata", function () {
     ok(false, "Unexpected loadeddata event");
     manager.finished(token);
   }, false);
@@ -41,16 +43,21 @@ function startTest(test, token) {
     ok(false, "Unexpected ended event");
     manager.finished(token);
   }, false);
 
   v.src = test.name; // implicitly starts a load.
 }
 
 SimpleTest.waitForExplicitFinish();
-SpecialPowers.pushPrefEnv({"set": [["media.cache_size", 40000]]}, beginTest);
+SpecialPowers.pushPrefEnv({
+  "set": [
+    ["media.cache_size", 40000],
+    ["dom.MediaError.message.enabled", true]
+  ]
+}, beginTest);
 function beginTest() {
   manager.runTests(gDecodeErrorTests, startTest);
 }
 </script>
 </pre>
 </body>
 </html>