diff --git a/src/devices/cpu/sm510/sm500.h b/src/devices/cpu/sm510/sm500.h
index d549c21103a..6514a6e1b78 100644
--- a/src/devices/cpu/sm510/sm500.h
+++ b/src/devices/cpu/sm510/sm500.h
@@ -84,7 +84,7 @@ protected:
 	virtual void clock_melody() override;
 
 	virtual void reset_vector() override { do_branch(0, 0xf, 0); }
-	virtual void wakeup_vector() override { do_branch(0, 0, 0); }
+	virtual void wakeup_vector() override { m_cb = 0; do_branch(0, 0, 0); }
 
 	// lcd driver
 	virtual void lcd_update() override;