diff --git a/package.json b/package.json
index 46e500f..336de6e 100644
--- a/package.json
+++ b/package.json
@@ -49,7 +49,7 @@
     "test-watch": "git ls-files | entr npm run test",
     "update-snapshots": "ava --timeout=1m --update-snapshots test/markdownlint-cli2-test-exec.mjs test/markdownlint-cli2-test-fs.mjs test/markdownlint-cli2-test-main.mjs",
     "webworker": "cd webworker && webpack --mode none",
-    "webworker-install": "npm install --no-package-lock --no-save path-browserify setimmediate stream-browserify util webpack-cli && cpy ./node_modules/setimmediate/setImmediate.js ./webworker/setImmediate.cjs --flat"
+    "webworker-install": "npm install --no-package-lock --no-save path-browserify setimmediate stream-browserify util webpack-cli && cpy ./node_modules/setimmediate/setImmediate.js ./webworker --flat --rename=setImmediate.cjs"
   },
   "engines": {
     "node": ">=18"
diff --git a/test/fs-virtual-test.mjs b/test/fs-virtual-test.mjs
index 88860c7..ac33a79 100644
--- a/test/fs-virtual-test.mjs
+++ b/test/fs-virtual-test.mjs
@@ -4,7 +4,7 @@ import path from "node:path";
 import { promisify } from "node:util";
 import test from "ava";
 import { __filename } from "./esm-helpers.mjs";
-import FsVirtual from "../webworker/fs-virtual.mjs";
+import FsVirtual from "../webworker/fs-virtual.cjs";
 
 const mockPath = "/mock";
 const thisFile = path.basename(__filename(import.meta));
diff --git a/test/markdownlint-cli2-test.mjs b/test/markdownlint-cli2-test.mjs
index fbf43b6..91301f9 100644
--- a/test/markdownlint-cli2-test.mjs
+++ b/test/markdownlint-cli2-test.mjs
@@ -12,7 +12,7 @@ import { "main" as markdownlintCli2 } from "../markdownlint-cli2.mjs";
 import jsoncParse from "../parsers/jsonc-parse.mjs";
 import yamlParse from "../parsers/yaml-parse.mjs";
 import FsMock from "./fs-mock.mjs";
-import FsVirtual from "../webworker/fs-virtual.mjs";
+import FsVirtual from "../webworker/fs-virtual.cjs";
 import firstLine from "./customRules/rules/first-line.cjs";
 
 const schemaIdVersionRe = /^.*v(?<version>\d+\.\d+\.\d+).*$/u;
diff --git a/webworker/fs-virtual.mjs b/webworker/fs-virtual.cjs
similarity index 96%
rename from webworker/fs-virtual.mjs
rename to webworker/fs-virtual.cjs
index 8435a5f..14d1ef3 100644
--- a/webworker/fs-virtual.mjs
+++ b/webworker/fs-virtual.cjs
@@ -1,5 +1,7 @@
 // @ts-check
 
+"use strict";
+
 const dirent = (path, directory) => {
   const name = path.replace(/^.*\//u, "");
   return {
@@ -97,4 +99,6 @@ class FsVirtual {
   }
 }
 
-export default FsVirtual;
+if (typeof module !== "undefined") {
+  module.exports = FsVirtual;
+}
diff --git a/webworker/module-stub.cjs b/webworker/module-stub.cjs
new file mode 100644
index 0000000..fec9487
--- /dev/null
+++ b/webworker/module-stub.cjs
@@ -0,0 +1,8 @@
+// @ts-check
+
+"use strict";
+
+module.exports = {
+  // @ts-ignore
+  "createRequire": () => require
+};
diff --git a/webworker/process-stub.cjs b/webworker/process-stub.cjs
index f4245d0..6db9393 100644
--- a/webworker/process-stub.cjs
+++ b/webworker/process-stub.cjs
@@ -3,6 +3,7 @@
 "use strict";
 
 module.exports = {
+  "argv": [],
   "cwd": () => "/",
   "env": {},
   "versions": {
diff --git a/webworker/webpack.config.cjs b/webworker/webpack.config.cjs
index 336498f..6b9377b 100644
--- a/webworker/webpack.config.cjs
+++ b/webworker/webpack.config.cjs
@@ -51,7 +51,7 @@ module.exports = {
     "fallback": {
       "buffer": false,
       "fs": false,
-      "module": false,
+      "module": require.resolve("./module-stub.cjs"),
       "os": require.resolve("./os-stub.cjs"),
       "path": require.resolve("path-browserify"),
       "process": require.resolve("./process-stub.cjs"),