diff --git a/drivers/siox/siox.h b/drivers/siox/siox.h
index c674bf6fb119..f08b43b713c5 100644
--- a/drivers/siox/siox.h
+++ b/drivers/siox/siox.h
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de>
  */