diff --git a/include/wx/gtk/notebook.h b/include/wx/gtk/notebook.h
index 035520de8f..1f8148d18c 100644
--- a/include/wx/gtk/notebook.h
+++ b/include/wx/gtk/notebook.h
@@ -139,9 +139,6 @@ public:
 
   // implementation
   // --------------
-    // callbacks
-  void OnSize(wxSizeEvent&);
-
     // base class virtuals
   virtual void AddChild(wxWindow *child);
   virtual void SetConstraintSizes(bool recurse);
diff --git a/include/wx/gtk1/notebook.h b/include/wx/gtk1/notebook.h
index 035520de8f..1f8148d18c 100644
--- a/include/wx/gtk1/notebook.h
+++ b/include/wx/gtk1/notebook.h
@@ -139,9 +139,6 @@ public:
 
   // implementation
   // --------------
-    // callbacks
-  void OnSize(wxSizeEvent&);
-
     // base class virtuals
   virtual void AddChild(wxWindow *child);
   virtual void SetConstraintSizes(bool recurse);