diff --git a/library/L3_Common.ttcn b/library/L3_Common.ttcn
index 01f0a34..0a80593 100644
--- a/library/L3_Common.ttcn
+++ b/library/L3_Common.ttcn
@@ -1,3 +1,14 @@
+/* Common L3 helper functions in TTCN-3
+ * (C) 2018 Harald Welte <laforge@gnumonks.org>
+ * contributions by sysmocom - s.f.m.c. GmbH
+ * 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 L3_Common {
 
 import from Osmocom_Types all;