diff --git a/metropolis/cli/metroctl/cmd_cluster.go b/metropolis/cli/metroctl/cmd_cluster.go
index e82cb95..a474061 100644
--- a/metropolis/cli/metroctl/cmd_cluster.go
+++ b/metropolis/cli/metroctl/cmd_cluster.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package main
 
 import "github.com/spf13/cobra"