diff --git a/include/wx/univ/dialog.h b/include/wx/univ/dialog.h
index fb43ddb039..c1e08230c2 100644
--- a/include/wx/univ/dialog.h
+++ b/include/wx/univ/dialog.h
@@ -71,7 +71,7 @@ public:
     // returns TRUE if we're in a modal loop
     bool IsModalShowing() const;
 
-    bool Show(bool show);
+    bool Show(bool show = TRUE);
 
     // implementation only from now on
     // -------------------------------