diff --git a/dom/media/MediaEventSource.h b/dom/media/MediaEventSource.h
index 185fa9639de..be13898031c 100644
--- a/dom/media/MediaEventSource.h
+++ b/dom/media/MediaEventSource.h
@@ -15,6 +15,7 @@
 
 #include "nsISupportsImpl.h"
 #include "nsTArray.h"
+#include "nsThreadUtils.h"
 
 namespace mozilla {