diff --git a/doc/copyright.texi b/doc/copyright.texi
index 44721f783..92b887801 100644
--- a/doc/copyright.texi
+++ b/doc/copyright.texi
@@ -16,6 +16,7 @@
 
 @copyrightstart
 @verbatim
+SPDX-License-Identifier: BSD-3-Clause
 
 Copyright (c) 1997-2011 Kungliga Tekniska Högskolan 
 (Royal Institute of Technology, Stockholm, Sweden).