diff --git a/src/core/all-units.h b/src/core/all-units.h
index ed8350ebe0d9c..23c1999b692f0 100644
--- a/src/core/all-units.h
+++ b/src/core/all-units.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
 #pragma once
 
 #include "unit.h"