diff --git a/tools/toolchains/mbed_toolchain.py b/tools/toolchains/mbed_toolchain.py
index af06e39603..6018648e2d 100755
--- a/tools/toolchains/mbed_toolchain.py
+++ b/tools/toolchains/mbed_toolchain.py
@@ -1,5 +1,6 @@
 """
 mbed SDK
+SPDX-License-Identifier: Apache-2.0
 Copyright (c) 2011-2013 ARM Limited
 
 Licensed under the Apache License, Version 2.0 (the "License");