diff --git a/library/AbisOML_Types.ttcn b/library/AbisOML_Types.ttcn
index 0d37f8a..c4fd81c 100644
--- a/library/AbisOML_Types.ttcn
+++ b/library/AbisOML_Types.ttcn
@@ -10,6 +10,8 @@
  *
  * Released under the terms of the GNU General Public License, Version 2 or
  * (at your option) any later version.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
  */
 
 import from General_Types all;