diff --git a/SubdividerPlugin.hh b/SubdividerPlugin.hh
index e17b02f1f226133f3ef5ab14e81e3fc5cf7f7aaf..0b25ffc46e35a10389a4a62d6de1e1e61e7f3d46 100644
--- a/SubdividerPlugin.hh
+++ b/SubdividerPlugin.hh
@@ -73,7 +73,7 @@ signals:
   void updateView();
   void updatedObject(int _id, const UpdateType& _type);
 
-  void addPickMode( const std::string _mode );
+  void addPickMode( const std::string& _mode );
 
   void log(Logtype _type, QString _message);
   void log(QString _message);