diff --git a/samples/mdi/mdi.cpp b/samples/mdi/mdi.cpp
index 892bdd5537..34e515c034 100644
--- a/samples/mdi/mdi.cpp
+++ b/samples/mdi/mdi.cpp
@@ -417,7 +417,8 @@ void MyChild::OnQuit(wxCommandEvent& WXUNUSED(event))
 
 void MyChild::OnRefresh(wxCommandEvent& event)
 {
-    Refresh();
+    if ( canvas )
+        canvas->Refresh();
 }
 
 void MyChild::OnActivate(wxActivateEvent& event)