diff --git a/src/osx/carbon/frame.cpp b/src/osx/carbon/frame.cpp
index 2c9e0f3926..09cd082182 100644
--- a/src/osx/carbon/frame.cpp
+++ b/src/osx/carbon/frame.cpp
@@ -225,8 +225,10 @@ void wxFrame::AttachMenuBar( wxMenuBar *menuBar )
 {
 #if wxOSX_USE_CARBON
     wxFrame* tlf = wxDynamicCast( wxNonOwnedWindow::GetFromWXWindow( (WXWindow) FrontNonFloatingWindow() ) , wxFrame );
+#elif wxOSX_USE_COCOA
+    wxFrame* tlf = wxDynamicCast( wxNonOwnedWindow::GetFromWXWindow( wxOSXGetMainWindow() ) , wxFrame );
 #else
-    wxFrame* tlf = (wxFrame*) wxTheApp->GetTopWindow();
+    wxFrame* tlf = wxDynamicCast( wxTheApp->GetTopWindow(), wxFrame );
 #endif
     bool makeCurrent = false;