diff --git a/library/GSM_Types.ttcn b/library/GSM_Types.ttcn
index 88be975..3e24f81 100644
--- a/library/GSM_Types.ttcn
+++ b/library/GSM_Types.ttcn
@@ -1,7 +1,14 @@
 /* Encoding/Decoding routines for GSM System Information messages
- * according to 3GPP TS 44.018 Version 12.3.0 Release 12 */
-
-/* (C) 2017 by Harald Welte <laforge@gnumonks.org> */
+ * according to 3GPP TS 44.018 Version 12.3.0 Release 12
+ *
+ * (C) 2017-2018 Harald Welte <laforge@gnumonks.org>
+ * All rights reserved.
+ *
+ * Released under the terms of GNU General Public License, Version 2 or
+ * (at your option) any later version.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
 
 module GSM_Types {