diff --git a/library/L1CTL_PortType.ttcn b/library/L1CTL_PortType.ttcn
index a366a1b..bdcf024 100644
--- a/library/L1CTL_PortType.ttcn
+++ b/library/L1CTL_PortType.ttcn
@@ -1,4 +1,14 @@
-/* dual-faced port that wraps an Unixdomain port and encodes/decodes L1CTL */
+/* dual-faced port that wraps an Unixdomain port and encodes/decodes L1CTL
+ * (C) 2017-2019 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 L1CTL_PortType {
 	import from L1CTL_Types all;
 	import from UD_PortType all;