diff --git a/.gitignore b/.gitignore
index 1ff9c6b..9f2d90d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,4 +6,4 @@ node_modules
 
 /index.js
 /index.mjs
-/src/index.js
+/src/index.ts
diff --git a/bin/index.js b/bin/index.ts
similarity index 58%
rename from bin/index.js
rename to bin/index.ts
index 938a52c..863500e 100644
--- a/bin/index.js
+++ b/bin/index.ts
@@ -1,22 +1,30 @@
 // @ts-check
-const fs = require('fs');
-const { join, dirname } = require('path');
-const DB = require('mime-db');
+/// <reference types="node" />
+import { join, dirname, resolve } from 'node:path';
+import { spawnSync } from 'node:child_process';
+import * as fs from 'node:fs';
+import DB from 'mime-db';
 
-const input = join(__dirname, '../src/$index.js');
-const output = join(__dirname, '../src/index.js');
-const denomod = join(__dirname, '../deno/mod.ts');
+const ROOT = resolve('.');
+
+const input = join(ROOT, 'src/$index.ts');
+const denomod = join(ROOT, 'deno/mod.ts');
+
+function write(file: string, data: string) {
+	let f = resolve(ROOT, file);
+	fs.writeFileSync(f, data);
+	console.log('~> "%s" created', file);
+}
 
 // iana > mimedb > apache > nginx
 // https://github.com/jshttp/mime-types/blob/master/index.js#L156
-const scores = { nginx: 1, apache: 2, iana: 4 };
-
-/**
- * @param {string} prev
- * @param {string} next
- * @return {string}
- */
-function compare(prev, next) {
+const SOURCES = {
+	nginx: 1,
+	apache: 2,
+	iana: 4,
+};
+
+function compare(prev: string, next: string): string {
 	let [p1] = prev.split('/', 1);
 	let [p2] = next.split('/', 1);
 
@@ -28,8 +36,8 @@ function compare(prev, next) {
 		if (p2 === 'application') return next;
 	}
 	// compare sources
-	let s1 = scores[DB[prev].source] || 3;
-	let s2 = scores[DB[next].source] || 3;
+	let s1 = SOURCES[DB[prev].source] || 3;
+	let s2 = SOURCES[DB[next].source] || 3;
 	if (s1 !== s2) return s2 > s1 ? next : prev;
 	return prev.length >= next.length ? next : prev;
 }
@@ -37,8 +45,8 @@ function compare(prev, next) {
 let dict = {};
 let ignore = /[/](x-|vnd\.)/;
 
-let mtype, arr;
-let i=0, extn, prev;
+let mtype: string, arr: string[];
+let i=0, extn: string, prev: string;
 
 for (mtype in DB) {
 	if (ignore.test(mtype)) continue;
@@ -50,7 +58,7 @@ for (mtype in DB) {
 		extn = arr[i];
 		prev = dict[extn];
 
-		if (prev) {
+		if (prev && prev !== mtype) {
 			let msg = `Found existing "${extn}" value:`;
 			msg += `\n   (prev) "${prev}"`;
 			msg += `\n   (next) "${mtype}"`;
@@ -65,10 +73,14 @@ for (mtype in DB) {
 
 let content = fs.readFileSync(input, 'utf8').replace(
 	'{}', JSON.stringify(dict, null, 2)
-);
+) + '\n';
+
+let esm = content + 'export { mimes, lookup };\n';
+let cjs = content + 'exports.mimes = mimes;\nexports.lookup = lookup;\n';
 
-fs.writeFileSync(output, content);
-console.log('~> "src/index.js" created');
+// build exports
+write('index.mjs', esm);
+write('index.js', cjs);
 
 let denodir = dirname(denomod);
 fs.existsSync(denodir) || fs.mkdirSync(denodir);
@@ -76,20 +88,22 @@ fs.existsSync(denodir) || fs.mkdirSync(denodir);
 fs.copyFileSync('readme.md', join(denodir, 'readme.md'));
 console.log('\n~> "deno/readme.md" created');
 
-fs.writeFileSync(denomod, content.replace(
+write('deno/mod.ts', esm.replace(
 	'function lookup(extn) {',
 	'function lookup(extn: string): string | undefined {',
 ).replace(
 	'const mimes = {',
 	'const mimes: Record<string, string> = {',
 ));
-console.log('~> "deno/mod.ts" created');
 
 if (!process.env.CI) {
 	try {
-		require('child_process').spawnSync('deno', ['fmt', denomod]);
+		spawnSync('deno', ['fmt', denomod], { cwd: ROOT });
 		console.log('\n~> $ deno fmt "deno/mod.ts"');
 	} catch (err) {
 		console.log('[deno]', err.stack);
 	}
 }
+
+fs.copyFileSync(denomod, 'src/index.ts');
+console.log('\n~> "src/index.ts" created');
diff --git a/bin/package.json b/bin/package.json
index b37628c..d4df2ed 100644
--- a/bin/package.json
+++ b/bin/package.json
@@ -1,6 +1,7 @@
 {
   "private": true,
   "devDependencies": {
+    "@types/node": "20.10.5",
     "mime-db": "1.49.0"
   }
 }
diff --git a/deno/mod.ts b/deno/mod.ts
index 445dc6c..fe953ea 100644
--- a/deno/mod.ts
+++ b/deno/mod.ts
@@ -1,4 +1,4 @@
-export const mimes: Record<string, string> = {
+const mimes: Record<string, string> = {
   "ez": "application/andrew-inset",
   "aw": "application/applixware",
   "atom": "application/atom+xml",
@@ -407,8 +407,10 @@ export const mimes: Record<string, string> = {
   "webm": "video/webm",
 };
 
-export function lookup(extn: string): string | undefined {
+function lookup(extn: string): string | undefined {
   let tmp = ("" + extn).trim().toLowerCase();
   let idx = tmp.lastIndexOf(".");
   return mimes[!~idx ? tmp : tmp.substring(++idx)];
 }
+
+export { lookup, mimes };
diff --git a/package.json b/package.json
index 3204e56..4531636 100644
--- a/package.json
+++ b/package.json
@@ -29,8 +29,8 @@
     "node": ">=10"
   },
   "scripts": {
-    "build": "node bin && bundt",
-    "test": "uvu -r esm test"
+    "build": "tsm bin/index.ts",
+    "test": "uvu -r tsm test"
   },
   "keywords": [
     "mime",
@@ -38,8 +38,7 @@
     "mimetype"
   ],
   "devDependencies": {
-    "bundt": "1.1.1",
-    "esm": "3.2.25",
+    "tsm": "2.3.0",
     "uvu": "0.5.2"
   }
 }
diff --git a/src/$index.js b/src/$index.ts
similarity index 70%
rename from src/$index.js
rename to src/$index.ts
index e9f7193..9a76cae 100644
--- a/src/$index.js
+++ b/src/$index.ts
@@ -1,6 +1,6 @@
-export const mimes = {};
+const mimes = {};
 
-export function lookup(extn) {
+function lookup(extn) {
 	let tmp = ('' + extn).trim().toLowerCase();
 	let idx = tmp.lastIndexOf('.');
 	return mimes[!~idx ? tmp : tmp.substring(++idx)];
diff --git a/test/index.js b/test/index.ts
similarity index 100%
rename from test/index.js
rename to test/index.ts