diff --git a/src/frontends/qt3/lyx_gui.C b/src/frontends/qt3/lyx_gui.C
index 339c09ca5d..34c9f7a50e 100644
--- a/src/frontends/qt3/lyx_gui.C
+++ b/src/frontends/qt3/lyx_gui.C
@@ -237,7 +237,7 @@ void start(string const & batch, vector<string> const & files,
 	view.setGeometry(posx, posy, width, height);
 
 	if (maximize)
-		view.setWindowState(WindowMaximized);
+		view.setWindowState(Qt::WindowMaximized);
 
 	view.show();