diff --git a/programs/adc_test.py b/programs/adc_test.py
index b4f6348c192139bbc786820106644e5f7db283ca..35707c0234467430219a8d791eabe0339042380d 100644
--- a/programs/adc_test.py
+++ b/programs/adc_test.py
@@ -1,3 +1,4 @@
+# This file is licensed under the Apache License, Version 2.0
 # based on https://github.com/jbentham/pico/blob/main/rp_adc_test.py
 # which is  Copyright (c) 2021 Jeremy P Bentham and licensed under the Apache License, Version 2.0