diff --git a/Transceiver52M/radioInterfaceResamp.cpp b/Transceiver52M/radioInterfaceResamp.cpp
index 8ae4aa1..e2f69f2 100644
--- a/Transceiver52M/radioInterfaceResamp.cpp
+++ b/Transceiver52M/radioInterfaceResamp.cpp
@@ -6,6 +6,8 @@
  *
  * Author: Tom Tsou <tom@tsou.cc>
  *
+ * SPDX-License-Identifier: AGPL-3.0+
+ *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or