diff --git a/kernel/user.c b/kernel/user.c
index 88b834f..78b17e3 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * The "user cache".
  *