diff --git a/sdr/CMakeLists.txt b/sdr/CMakeLists.txt
index 24eaf34d7..5f8bd4f2f 100644
--- a/sdr/CMakeLists.txt
+++ b/sdr/CMakeLists.txt
@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/sdr/CMakeLists.txt
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # 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/sdr/Make.defs b/sdr/Make.defs
index 0a48f77f2..e78ed07c7 100644
--- a/sdr/Make.defs
+++ b/sdr/Make.defs
@@ -1,6 +1,8 @@
 ############################################################################
 # apps/sdr/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # 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/sdr/Makefile b/sdr/Makefile
index 6a32e03fd..9dbadc55f 100644
--- a/sdr/Makefile
+++ b/sdr/Makefile
@@ -1,6 +1,8 @@
 ############################################################################
 # apps/sdr/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # 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/sdr/liquid_dsp/Make.defs b/sdr/liquid_dsp/Make.defs
index eff26a4a8..f61ca389a 100644
--- a/sdr/liquid_dsp/Make.defs
+++ b/sdr/liquid_dsp/Make.defs
@@ -1,6 +1,7 @@
 ############################################################################
 # apps/sdr/liquid_dsp/Make.defs
-# Adds selected applications to apps/ build
+#
+# SPDX-License-Identifier: Apache-2.0
 #
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
diff --git a/sdr/liquid_dsp/Makefile b/sdr/liquid_dsp/Makefile
index 2da12bee3..8a257b304 100644
--- a/sdr/liquid_dsp/Makefile
+++ b/sdr/liquid_dsp/Makefile
@@ -1,6 +1,8 @@
 ###########################################################################
 # apps/sdr/liquid_dsp/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # 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/sdr/liquid_dsp/config.h b/sdr/liquid_dsp/config.h
index 50f7f4433..50e5f1b71 100644
--- a/sdr/liquid_dsp/config.h
+++ b/sdr/liquid_dsp/config.h
@@ -1,6 +1,8 @@
 /****************************************************************************
  * apps/sdr/liquid_dsp/config.h
  *
+ * SPDX-License-Identifier: Apache-2.0
+ *
  * 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