diff --git a/doc/copyright.texi b/doc/copyright.texi
index af6d626de..df0de10e8 100644
--- a/doc/copyright.texi
+++ b/doc/copyright.texi
@@ -170,6 +170,7 @@ SUCH DAMAGE.
 GSS-API mechglue layer.
 
 @verbatim
+SPDX-License-Identifier: BSD-2-Clause
 
 Copyright (c) 2005 Doug Rabson
 All rights reserved.