--- a/dom/media/test/eme.js
+++ b/dom/media/test/eme.js
@@ -234,16 +234,17 @@ function LoadTest(test, elem, token, loa
 {
   if (!test.tracks) {
     ok(false, token + " test does not have a tracks list");
     return Promise.reject();
   }
 
   var ms = new MediaSource();
   elem.src = URL.createObjectURL(ms);
+  elem.crossOrigin = test.crossOrigin || false;
 
   return new Promise(function (resolve, reject) {
     ms.addEventListener("sourceopen", function () {
       Log(token, "sourceopen");
       Promise.all(test.tracks.map(function(track) {
         return AppendTrack(test, ms, track, token, loadParams);
       })).then(function() {
         if (loadParams && loadParams.noEndOfStream) {
@@ -277,17 +278,16 @@ function EMEPromiseAll(v, token, promise
     removeNodeAndSource(v);
     manager.finished(token);
   });
 }
 
 function SetupEME(test, token, params)
 {
   var v = document.createElement("video");
-  v.crossOrigin = test.crossOrigin || false;
   v.sessions = [];
 
   v.closeSessions = function() {
     return Promise.all(v.sessions.map(s => s.close().then(() => s.closed))).then(
       () => {
         v.setMediaKeys(null);
         if (v.parentNode) {
           v.remove();