diff --git a/include/net/netns/core.h b/include/net/netns/core.h
index 78eb1ff..0ad4d0c 100644
--- a/include/net/netns/core.h
+++ b/include/net/netns/core.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_CORE_H__
 #define __NETNS_CORE_H__