--- a/dom/media/TextTrackList.h
+++ b/dom/media/TextTrackList.h
@@ -62,17 +62,17 @@ public:
   nsresult DispatchTrackEvent(nsIDOMEvent* aEvent);
   void CreateAndDispatchChangeEvent();
   void SetCuesInactive();
 
   IMPL_EVENT_HANDLER(change)
   IMPL_EVENT_HANDLER(addtrack)
   IMPL_EVENT_HANDLER(removetrack)
 
-  bool mPendingTextTrackChange;
+  MOZ_INIT_OUTSIDE_CTOR bool mPendingTextTrackChange;
 
 private:
   ~TextTrackList();
 
   nsTArray< RefPtr<TextTrack> > mTextTracks;
   RefPtr<TextTrackManager> mTextTrackManager;
 
   void CreateAndDispatchTrackEventRunner(TextTrack* aTrack,