diff --git a/include/linux/if_tunnel.h b/include/linux/if_tunnel.h
index 712710b..2660652 100644
--- a/include/linux/if_tunnel.h
+++ b/include/linux/if_tunnel.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _IF_TUNNEL_H_
 #define _IF_TUNNEL_H_