diff --git a/chatdialog.h b/chatdialog.h
index 0f65426..4c24335 100644
--- a/chatdialog.h
+++ b/chatdialog.h
@@ -11,7 +11,7 @@
 	ChatDialog(QWidget *parent = 0);
 
 public slots:
-  void appendMessage(SyncDemo::ChatMessage &msg);
+  void appendMessage(const SyncDemo::ChatMessage &msg);
   void updateTreeView();
 
 private slots: