diff --git a/.eslintrc.json b/.eslintrc.json
index efc2ee546..50eef44ec 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -6,7 +6,7 @@
   },
   "parserOptions": {
     "ecmaVersion": 2019,
-    "sourceType": "script"
+    "sourceType": "module"
   },
   "extends": "eslint:recommended",
   "rules": {
@@ -30,9 +30,6 @@
       "env": {
         "browser": true,
         "node": false
-      },
-      "parserOptions": {
-        "sourceType": "module"
       }
     }
   ]
diff --git a/build/vnu-jar.js b/build/vnu-jar.mjs
similarity index 92%
rename from build/vnu-jar.js
rename to build/vnu-jar.mjs
index d725a378c..fe9661f66 100644
--- a/build/vnu-jar.js
+++ b/build/vnu-jar.mjs
@@ -6,10 +6,8 @@
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
  */
 
-'use strict'
-
-const { execFile, spawn } = require('node:child_process')
-const vnu = require('vnu-jar')
+import { execFile, spawn } from 'node:child_process'
+import vnu from 'vnu-jar'
 
 execFile('java', ['-version'], (error, stdout, stderr) => {
   if (error) {
diff --git a/package.json b/package.json
index db1f90aaa..037a6cc65 100644
--- a/package.json
+++ b/package.json
@@ -24,12 +24,12 @@
     "serve": "hugo server --port 4000 --disableFastRender",
     "serve-only": "npx sirv-cli _site --port 4000",
     "test": "npm-run-all build --parallel --continue-on-error --aggregate-output test-*",
-    "test-eslint": "eslint --ignore-path .gitignore --cache --cache-location .cache/.eslintcache --report-unused-disable-directives .",
+    "test-eslint": "eslint --ignore-path .gitignore --cache --cache-location .cache/.eslintcache --report-unused-disable-directives --ext .js,.mjs .",
     "test-fusv": "fusv src/assets/scss/",
     "test-stylelint": "stylelint src/assets/scss/ --cache --cache-location .cache/.stylelintcache",
     "test-markdownlint": "markdownlint-cli2 \"**/*.md\" \"!**/node_modules/**\"",
     "test-linkinator": "linkinator _site --recurse --silent --skip \"^(?!http://localhost)\"",
-    "test-vnu": "node build/vnu-jar.js",
+    "test-vnu": "node build/vnu-jar.mjs",
     "test-lockfile-lint": "lockfile-lint --allowed-hosts npm --allowed-schemes https: --empty-hostname false --type npm --path package-lock.json",
     "netlify": "cross-env-shell HUGO_BASEURL=$DEPLOY_PRIME_URL npm run build"
   },