diff --git a/format.go b/format.go
index 3693259..17440de 100644
--- a/format.go
+++ b/format.go
@@ -1,3 +1,7 @@
+// Copyright (C) 2016-2017 Vladimir Bauer
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package mpb
 
 import "fmt"