diff --git a/net/tlsdial/deps_test.go b/net/tlsdial/deps_test.go
new file mode 100644
index 000000000..6c34c9bd7
--- /dev/null
+++ b/net/tlsdial/deps_test.go
@@ -0,0 +1,10 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build for_go_mod_tidy_only
+// +build for_go_mod_tidy_only
+
+package tlsdial
+
+import _ "filippo.io/mkcert"