diff --git a/ipc/shm.c b/ipc/shm.c
index badac46..bd65275 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * linux/ipc/shm.c
  * Copyright (C) 1992, 1993 Krishna Balasubramanian