diff --git a/metropolis/test/swtpm/certtool/main.go b/metropolis/test/swtpm/certtool/main.go
index 5079c54..600d9aa 100644
--- a/metropolis/test/swtpm/certtool/main.go
+++ b/metropolis/test/swtpm/certtool/main.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package main
 
 // Minimal GnuTLS certtool-like tool in Go. Implements only what's needed for
diff --git a/metropolis/test/swtpm/swtpm_cert/asn1.go b/metropolis/test/swtpm/swtpm_cert/asn1.go
index 4136a25..1fe87ee 100644
--- a/metropolis/test/swtpm/swtpm_cert/asn1.go
+++ b/metropolis/test/swtpm/swtpm_cert/asn1.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package main
 
 import (
diff --git a/metropolis/test/swtpm/swtpm_cert/main.go b/metropolis/test/swtpm/swtpm_cert/main.go
index 8d5663b..e6d1a01 100644
--- a/metropolis/test/swtpm/swtpm_cert/main.go
+++ b/metropolis/test/swtpm/swtpm_cert/main.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package main
 
 // swtpm_cert (from swtpm project) reimplemented in Go.