diff --git a/metropolis/node/validation_test.go b/metropolis/node/validation_test.go
index 1a9765e..1a5f84d 100644
--- a/metropolis/node/validation_test.go
+++ b/metropolis/node/validation_test.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package node
 
 import (