diff --git a/src/osd/sdl/window.h b/src/osd/sdl/window.h
index ae42d1ccd7a..d1c28c06e95 100644
--- a/src/osd/sdl/window.h
+++ b/src/osd/sdl/window.h
@@ -45,7 +45,7 @@ public:
 
 	int window_init();
 
-	void update();
+	void update() override;
 	void toggle_full_screen();
 	void modify_prescale(int dir);
 	void resize(INT32 width, INT32 height);