diff --git a/content/html/content/src/HTMLMediaElement.cpp b/content/html/content/src/HTMLMediaElement.cpp
index 6aa73df091bf..75eca9fd6720 100644
--- a/content/html/content/src/HTMLMediaElement.cpp
+++ b/content/html/content/src/HTMLMediaElement.cpp
@@ -1137,14 +1137,14 @@ nsresult HTMLMediaElement::LoadResource()
       ReportLoadError("MediaLoadInvalidURI", params, ArrayLength(params));
       return rv;
     }
-    mMediaSource = source.forget();
     nsRefPtr<MediaSourceDecoder> decoder = new MediaSourceDecoder(this);
-    if (!mMediaSource->Attach(decoder)) {
+    if (!source->Attach(decoder)) {
       // TODO: Handle failure: run "If the media data cannot be fetched at
       // all, due to network errors, causing the user agent to give up
       // trying to fetch the resource" section of resource fetch algorithm.
       return NS_ERROR_FAILURE;
     }
+    mMediaSource = source.forget();
     nsRefPtr<MediaResource> resource = new MediaSourceResource();
     return FinishDecoderSetup(decoder, resource, nullptr, nullptr);
   }
diff --git a/content/media/test/crashtests/926665.html b/content/media/test/crashtests/926665.html
new file mode 100644
index 000000000000..a8247b27e79e
--- /dev/null
+++ b/content/media/test/crashtests/926665.html
@@ -0,0 +1,26 @@
+<html>
+<head>
+<meta charset="UTF-8">
+<script style="display: none;" id="fuzz1" type="text/javascript;version=1.7">
+
+function boom()
+{
+    var mediaSource = new window.MediaSource();
+    var mediaSourceURL = URL.createObjectURL(mediaSource);
+    var v1 = document.createElement('video');
+    v1.src = mediaSourceURL;
+    mediaSource.addEventListener("sourceopen", function (e) {
+        var v2 = document.createElement('video');
+        v2.src = mediaSourceURL;
+        setTimeout(function () {
+            v2.src = "data:text/plain,1";
+            v1.src = "data:text/plain,2";
+        }, 0);
+    });
+}
+
+</script>
+</head>
+
+<body onload="boom();"></body>
+</html>
diff --git a/content/media/test/crashtests/crashtests.list b/content/media/test/crashtests/crashtests.list
index 4d1acbc64848..143e6588be17 100644
--- a/content/media/test/crashtests/crashtests.list
+++ b/content/media/test/crashtests/crashtests.list
@@ -59,3 +59,4 @@ load 910171-1.html
 load 920987.html
 skip-if(B2G) load oscillator-ended-1.html # intermittent B2G timeouts, bug 920338
 skip-if(B2G) load oscillator-ended-2.html # intermittent B2G timeouts, bug 920338
+test-pref(media.mediasource.enabled,true) load 926665.html
