diff --git a/tools/modulize.mjs b/tools/modulize.mjs
index 6746e2b..1549445 100644
--- a/tools/modulize.mjs
+++ b/tools/modulize.mjs
@@ -1,7 +1,9 @@
 import {stdin, argv} from 'node:process'
 import {streamToString} from '../etc/streamToString.js'
 
-const preamble = 'export default (((f) => f())(function () {'
+const preamble = `// ES6 Module converted from https://github.com/no-context/moo
+   export default (((f) => f())(function () {
+`
 const umd = await streamToString(stdin)
 const realStart = umd.indexOf(" 'use strict'")
-console.log(preamble + "\n" + umd.substring(realStart))
+console.log(preamble + umd.substring(realStart))