diff --git a/base/public/nsRepeater.h b/base/public/nsRepeater.h
index 3b25f04668e8..d72d45c1f2f0 100644
--- a/base/public/nsRepeater.h
+++ b/base/public/nsRepeater.h
@@ -19,9 +19,11 @@
 #ifndef nsRepeater_h___
 #define nsRepeater_h___
 
+#include "nscore.h"
+
 class EventRecord;
 
-class Repeater {
+class NS_BASE Repeater {
   public:
   
     Repeater();