diff --git a/include/wx/window.h b/include/wx/window.h
index b9a8332d5c..f2227aecb5 100644
--- a/include/wx/window.h
+++ b/include/wx/window.h
@@ -73,8 +73,6 @@ class WXDLLEXPORT wxWindow;
 class WXDLLEXPORT wxAccessible;
 #endif
 
-class WXDLLEXPORT wxWindowExtraData;
-
 // ----------------------------------------------------------------------------
 // helper stuff used by wxWindow
 // ----------------------------------------------------------------------------
@@ -1314,9 +1312,8 @@ protected:
     // implements the window variants
     virtual void DoSetWindowVariant( wxWindowVariant variant ) ;
 
-    // Was a reserved pointer in 2.6.0, now used to hold extra data members
-    // without breaking compatibility.
-    wxWindowExtraData* m_extraData;
+    // Reserved for future use
+    void* m_windowReserved;
 
 private:
     // contains the last id generated by NewControlId
diff --git a/src/common/wincmn.cpp b/src/common/wincmn.cpp
index b46e7c9b51..c296441e77 100644
--- a/src/common/wincmn.cpp
+++ b/src/common/wincmn.cpp
@@ -216,9 +216,8 @@ wxWindowBase::wxWindowBase()
     // VZ: this one shouldn't exist...
     m_isBeingDeleted = false;
     
-    // Can be used in port specific wxWindow derived classes for holding extra
-    // data memebers.
-    m_extraData = NULL;
+    // Reserved for future use
+    m_windowReserved = NULL;
 }
 
 // common part of window creation process