diff --git a/cmd/cloudflared/tunnel/cmd.go b/cmd/cloudflared/tunnel/cmd.go
index 6d3deab7..e691f93f 100644
--- a/cmd/cloudflared/tunnel/cmd.go
+++ b/cmd/cloudflared/tunnel/cmd.go
@@ -195,6 +195,13 @@ func TunnelCommand(c *cli.Context) error {
 		return runClassicTunnel(sc)
 	}
 
+	if c.String("proxy-dns") != "" {
+		// NamedTunnelProperties are nil since proxy dns server does not need it.
+		// This is supported for legacy reasons: dns proxy server is not a tunnel and ideally should
+		// not run as part of cloudflared tunnel.
+		return StartServer(sc.c, buildInfo, nil, sc.log)
+	}
+
 	return errors.New(tunnelCmdErrorMessage)
 }