diff --git a/packages/webpack-css/index.js b/packages/webpack-css/index.js
index 7e4cb473..8da04bfc 100644
--- a/packages/webpack-css/index.js
+++ b/packages/webpack-css/index.js
@@ -1,4 +1,7 @@
-let CssMinimizerPlugin = require('css-minimizer-webpack-plugin')
+import CssMinimizerPlugin from 'css-minimizer-webpack-plugin'
+import { createRequire } from 'node:module'
+
+const require = createRequire(import.meta.url)
 
 const cssRule = {
   exclude: /\.module\.css$/,
@@ -44,4 +47,4 @@ let self = {
   name: '@size-limit/webpack-css'
 }
 
-module.exports = [self]
+export default [self]
diff --git a/packages/webpack-css/package.json b/packages/webpack-css/package.json
index 0c1797fc..6d6ac492 100644
--- a/packages/webpack-css/package.json
+++ b/packages/webpack-css/package.json
@@ -13,6 +13,7 @@
   "author": "Andrey Sitnik <andrey@sitnik.ru>",
   "license": "MIT",
   "repository": "ai/size-limit",
+  "type": "module",
   "engines": {
     "node": "^18.0.0 || >=20.0.0"
   },
diff --git a/packages/webpack-css/test/index.test.js b/packages/webpack-css/test/index.test.js
index 01166bd5..e6da758b 100644
--- a/packages/webpack-css/test/index.test.js
+++ b/packages/webpack-css/test/index.test.js
@@ -1,9 +1,14 @@
-let [webpack] = require('@size-limit/webpack')
-let { join } = require('path')
-let [file] = require('@size-limit/file')
-let rm = require('size-limit/rm')
+import filePlugins from '@size-limit/file'
+import webpackPlugins from '@size-limit/webpack'
+import { join } from 'node:path'
+import rm from 'size-limit/rm'
+import { afterEach, expect, it, vi } from 'vitest'
 
-let [webpackCss] = require('../')
+import webpackCssPlugins from '../'
+let [webpack] = webpackPlugins
+let [file] = filePlugins
+
+let [webpackCss] = webpackCssPlugins
 
 const DIST = join(process.cwd(), 'dist')
 
@@ -25,7 +30,7 @@ async function run(config) {
 }
 afterEach(async () => {
   await rm(DIST)
-  jest.clearAllMocks()
+  vi.clearAllMocks()
 })
 
 it('supports non-JS require', async () => {
@@ -38,7 +43,7 @@ it('supports non-JS require', async () => {
 })
 
 it('applies both `modifyWebpackConfig`', async () => {
-  let { DefinePlugin } = require('webpack')
+  let { DefinePlugin } = await import('webpack')
   let plugin = new DefinePlugin({
     TEST: 'true'
   })