diff --git a/mux.go b/mux.go
index 2c61ff9..fc3663d 100644
--- a/mux.go
+++ b/mux.go
@@ -1,3 +1,7 @@
+// Copyright 2009 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-GO file.
+
 package gemini
 
 import (