diff --git a/msr-smp.h b/msr-smp.h
index 23cb083..3dc2ad4 100644
--- a/msr-smp.h
+++ b/msr-smp.h
@@ -1,3 +1,9 @@
+// Copyright 2011-2021 Lawrence Livermore National Security, LLC and other
+// msr-safe Project Developers. See the top-level COPYRIGHT file for
+// details.
+//
+// SPDX-License-Identifier: GPL-2.0-only
+
 #ifndef MSR_SMP_INCLUDE
 #define MSR_SMP_INCLUDE