diff --git a/metropolis/test/util/rpc.go b/metropolis/test/util/rpc.go
index c31c935..e2558a3 100644
--- a/metropolis/test/util/rpc.go
+++ b/metropolis/test/util/rpc.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package util
 
 import (