diff --git a/src/mame/includes/vicdual.h b/src/mame/includes/vicdual.h
index 1bd6bc1b6c5..9748eaf1f7e 100644
--- a/src/mame/includes/vicdual.h
+++ b/src/mame/includes/vicdual.h
@@ -177,5 +177,5 @@ public:
 	DECLARE_MACHINE_START(nsub);
 	DECLARE_MACHINE_RESET(nsub);
 
-	virtual pen_t choose_pen(uint8_t x, uint8_t y, pen_t back_pen);
+	virtual pen_t choose_pen(uint8_t x, uint8_t y, pen_t back_pen) override;
 };