diff --git a/aht20/error.go b/aht20/error.go
index 832033d..946b4c2 100644
--- a/aht20/error.go
+++ b/aht20/error.go
@@ -1,3 +1,7 @@
+// Copyright 2024 The Periph Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
 package aht20
 
 import (