diff --git a/gtk2_ardour/au_pluginui.mm b/gtk2_ardour/au_pluginui.mm
index 9c8980cfff..9e9e45b3e5 100644
--- a/gtk2_ardour/au_pluginui.mm
+++ b/gtk2_ardour/au_pluginui.mm
@@ -851,14 +851,12 @@ AUPluginUI::parent_cocoa_window ()
 
 	resizable = false;
 
-	if (!toplevel || !toplevel->is_toplevel()) {
-		error << _("AUPluginUI: no top level window!") << endmsg;
+	if (toplevel && toplevel->is_toplevel()) {
+		toplevel->size_request (req);
+		toplevel->set_size_request (req.width, req.height);
+		dynamic_cast<Gtk::Window*>(toplevel)->set_resizable (false);
 	}
 
-	toplevel->size_request (req);
-	toplevel->set_size_request (req.width, req.height);
-	dynamic_cast<Gtk::Window*>(toplevel)->set_resizable (false);
-
 #endif
 	return 0;
 }