diff --git a/xpcom/string/public/nsBufferHandle.h b/xpcom/string/public/nsBufferHandle.h
index 0b2c04b9b792..93c574b2a804 100755
--- a/xpcom/string/public/nsBufferHandle.h
+++ b/xpcom/string/public/nsBufferHandle.h
@@ -184,7 +184,7 @@ struct nsStringAllocatorTraits<PRUnichar>
 // A small utility class for verifying that all reference counting of
 // shared buffer handles (which are not threadsafe) occurs on a single
 // thread.
-class nsSingleThreadVerifier
+class NS_COM nsSingleThreadVerifier
   {
     public:
       nsSingleThreadVerifier();