diff --git a/tools/include/linux/kern_levels.h b/tools/include/linux/kern_levels.h
index 3b9bade..778ecb9 100644
--- a/tools/include/linux/kern_levels.h
+++ b/tools/include/linux/kern_levels.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __KERN_LEVELS_H__
 #define __KERN_LEVELS_H__