diff --git a/mozilla/xpcom/ds/MANIFEST_IDL b/mozilla/xpcom/ds/MANIFEST_IDL
index 7cf12429970..da3fc2dc343 100644
--- a/mozilla/xpcom/ds/MANIFEST_IDL
+++ b/mozilla/xpcom/ds/MANIFEST_IDL
@@ -4,10 +4,8 @@ nsICollection.idl
 nsIEnumerator.idl
 nsIObserver.idl
 nsIObserverService.idl
-nsIProperties.idl
-nsIStopwatch.idl
-nsIProperties.idl
 nsIPersistentProperties2.idl
+nsIProperties.idl
+nsISerializable.idl
 nsIStopwatch.idl
-
 nsISupportsArray.idl