diff --git a/src/osd/windows/window.c b/src/osd/windows/window.c
index f3516ade783..7ff2cdb5ee7 100644
--- a/src/osd/windows/window.c
+++ b/src/osd/windows/window.c
@@ -1896,7 +1896,7 @@ static void set_fullscreen(win_window_info *window, int fullscreen)
 	adjust_window_position_after_major_change(window);
 }
 
-#ifdef USE_QTDEBUG
+#if (USE_QTDEBUG)
 bool winwindow_qt_filter(void *message)
 {
 	MSG *msg = (MSG *)message;