--- a/dom/media/TextTrack.cpp
+++ b/dom/media/TextTrack.cpp
@@ -145,19 +145,22 @@ TextTrack::AddCue(TextTrackCue& aCue)
     }
   }
   SetDirty();
 }
 
 void
 TextTrack::RemoveCue(TextTrackCue& aCue, ErrorResult& aRv)
 {
+  // Bug1304948, check the aCue belongs to the TextTrack.
+  mCueList->RemoveCue(aCue, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
   aCue.SetActive(false);
-
-  mCueList->RemoveCue(aCue, aRv);
   aCue.SetTrack(nullptr);
   if (mTextTrackList) {
     HTMLMediaElement* mediaElement = mTextTrackList->GetMediaElement();
     if (mediaElement) {
       mediaElement->NotifyCueRemoved(aCue);
     }
   }
   SetDirty();