diff --git a/include/wx/cocoa/listbox.h b/include/wx/cocoa/listbox.h
index 479362e40e..6ada4abc57 100644
--- a/include/wx/cocoa/listbox.h
+++ b/include/wx/cocoa/listbox.h
@@ -28,7 +28,7 @@ class WXDLLEXPORT wxListBox: public wxListBoxBase, protected wxCocoaNSTableView
 // initialization
 // ------------------------------------------------------------------------
 public:
-    wxListBox() { m_cocoaItems = NULL; }
+    wxListBox() { m_cocoaItems = NULL; m_cocoaDataSource = NULL; }
     wxListBox(wxWindow *parent, wxWindowID winid,
             const wxPoint& pos = wxDefaultPosition,
             const wxSize& size = wxDefaultSize,