diff --git a/headers/os/app/Messenger.h b/headers/os/app/Messenger.h
index 9deaf165c8..601ebe3b72 100644
--- a/headers/os/app/Messenger.h
+++ b/headers/os/app/Messenger.h
@@ -46,6 +46,10 @@
 class BHandler;
 class BLooper;
 
+namespace BPrivate {
+	class TRoster;
+};
+
 // BMessenger class ------------------------------------------------------------
 class BMessenger {
 public:	
@@ -87,7 +91,7 @@ public:
 	//----- Private or reserved -----------------------------------------
 private:
 	friend class BRoster;
-	friend class _TRoster_;
+	friend class BPrivate::TRoster;
 	friend class BMessage;
 	friend inline void _set_message_reply_(BMessage *, BMessenger);
 	friend status_t swap_data(type_code, void *, size_t, swap_action);