diff --git a/index.js b/index.js
index 0b4d2cc..3647c41 100644
--- a/index.js
+++ b/index.js
@@ -1,10 +1,6 @@
-'use strict'
-
-var visit = require('unist-util-visit')
-var position = require('unist-util-position')
-var toString = require('nlcst-to-string')
-
-module.exports = mentions
+import visit from 'unist-util-visit'
+import position from 'unist-util-position'
+import toString from 'nlcst-to-string'
 
 var genitive = /['’]s?$/i
 
@@ -12,7 +8,7 @@ var gh =
   /^@(?:[a-z\d]{1,2}|[a-z\d][a-z\d-]{1,37}[a-z\d])(\/(?:[a-z\d]{1,2}|[a-z\d][a-z\d-]{1,37}[a-z\d]))?$/i
 var tw = /^@\w{1,15}$/i
 
-function mentions(options) {
+export default function retextSyntaxMentions(options) {
   var style = (options || {}).style || 'github'
 
   if (typeof style === 'string') {
diff --git a/package.json b/package.json
index 983a2eb..706c571 100644
--- a/package.json
+++ b/package.json
@@ -26,6 +26,9 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
     "index.js"
   ],
@@ -43,7 +46,7 @@
     "tape": "^5.0.0",
     "unist-builder": "^2.0.0",
     "unist-util-remove-position": "^3.0.0",
-    "xo": "^0.37.0"
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
@@ -61,7 +64,10 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false
+    "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
+    }
   },
   "remarkConfig": {
     "plugins": [
diff --git a/test.js b/test.js
index d85e3b1..b674328 100644
--- a/test.js
+++ b/test.js
@@ -1,10 +1,8 @@
-'use strict'
-
-var test = require('tape')
-var retext = require('retext')
-var u = require('unist-builder')
-var clean = require('unist-util-remove-position')
-var mentions = require('.')
+import test from 'tape'
+import retext from 'retext'
+import u from 'unist-builder'
+import clean from 'unist-util-remove-position'
+import mentions from './index.js'
 
 var position = retext().use(mentions)
 var noPosition = retext().use(mentions).use(strip)