diff --git a/include/wx/event.h b/include/wx/event.h
index f937cca16c..92b58526e1 100644
--- a/include/wx/event.h
+++ b/include/wx/event.h
@@ -2356,7 +2356,7 @@ public:
         { return Disconnect(winid, wxID_ANY, eventType, func, userData, eventSink); }
 
     bool Disconnect(wxEventType eventType,
-                    wxObjectEventFunction func = NULL,
+                    wxObjectEventFunction func,
                     wxObject *userData = (wxObject *) NULL,
                     wxEvtHandler *eventSink = (wxEvtHandler *) NULL)
         { return Disconnect(wxID_ANY, eventType, func, userData, eventSink); }