--- a/dom/media/test/test_buffered.html
+++ b/dom/media/test/test_buffered.html
@@ -95,17 +95,17 @@ function startTest(test, token) {
   // we have deterministic behaviour.
   var onfetched = function(uri) {
     var v = document.createElement('video');
     v.autoplay = true;
     v._token = token;
     v.src = uri;
     v._name = test.name;
     v._test = test;
-    v.addEventListener("timeupdate", testBuffered, {once: true});
+    v.addEventListener("loadeddata", testBuffered, {once: true});
     document.body.appendChild(v);
   };
 
   manager.started(token);
   fetch(test.name, onfetched);
 }
 
 // Note: No need to set media test prefs, since we're using XHR to fetch