diff --git a/dom/workers/WorkerScope.h b/dom/workers/WorkerScope.h
index 101de795a15b..e49e3842290b 100644
--- a/dom/workers/WorkerScope.h
+++ b/dom/workers/WorkerScope.h
@@ -9,6 +9,7 @@
 
 #include "mozilla/dom/WorkerCommon.h"
 #include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/dom/DOMPrefs.h"
 #include "mozilla/dom/Headers.h"
 #include "mozilla/dom/RequestBinding.h"
 #include "nsWeakReference.h"