diff --git a/chacha20poly1305/internal/chacha20/chacha_test.go b/chacha20poly1305/internal/chacha20/chacha_test.go
index ca9663f..b80d34c 100644
--- a/chacha20poly1305/internal/chacha20/chacha_test.go
+++ b/chacha20poly1305/internal/chacha20/chacha_test.go
@@ -1,3 +1,7 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package chacha20
 
 import (