diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index 1ef4cc3..db0b5aa 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
  *