diff --git a/inertial/CMakeLists.txt b/inertial/CMakeLists.txt
index fb213b9ee..66cfc9e27 100644
--- a/inertial/CMakeLists.txt
+++ b/inertial/CMakeLists.txt
@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/inertial/CMakeLists.txt
 #
+# SPDX-License-Identifier: BSD-3-Clause
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more contributor
 # license agreements.  See the NOTICE file distributed with this work for
 # additional information regarding copyright ownership.  The ASF licenses this
diff --git a/inertial/Make.defs b/inertial/Make.defs
index 03113ac85..d19af3397 100644
--- a/inertial/Make.defs
+++ b/inertial/Make.defs
@@ -1,6 +1,8 @@
 ############################################################################
 # apps/inertial/Make.defs
 #
+# SPDX-License-Identifier: BSD-3-Clause
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The
diff --git a/inertial/Makefile b/inertial/Makefile
index e05b10cd2..e12c1d623 100644
--- a/inertial/Makefile
+++ b/inertial/Makefile
@@ -1,6 +1,8 @@
 ############################################################################
 # apps/inertial/Makefile
 #
+# SPDX-License-Identifier: BSD-3-Clause
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The
diff --git a/inertial/madgwick/Make.defs b/inertial/madgwick/Make.defs
index 814fb83af..e16d25d84 100644
--- a/inertial/madgwick/Make.defs
+++ b/inertial/madgwick/Make.defs
@@ -1,6 +1,8 @@
 ############################################################################
 # apps/inertial/madgwick/Make.defs
 #
+# SPDX-License-Identifier: BSD-3-Clause
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The
diff --git a/inertial/madgwick/Makefile b/inertial/madgwick/Makefile
index 936d28219..38dac5227 100644
--- a/inertial/madgwick/Makefile
+++ b/inertial/madgwick/Makefile
@@ -1,6 +1,8 @@
 ############################################################################
 # apps/inertial/madgwick/Makefile
 #
+# SPDX-License-Identifier: BSD-3-Clause
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The