diff --git a/eslint.config.mjs b/eslint.config.mjs
index 99ee8fef..1eb5230f 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -21,10 +21,20 @@ export default [
       },
     },
   },
+  {
+    files: ['**/*.cjs'],
+    languageOptions: {
+      sourceType: 'script',
+    },
+  },
   { languageOptions: { globals: globals.node } },
   pluginJs.configs.recommended,
   eslintConfigPrettier,
   {
-    ignores: ['tests/fixture/*', 'tests/fixture-ts/*', 'files/ember-cli-build.js'],
+    ignores: [
+      'tests/fixture/*',
+      'tests/fixture-ts/*',
+      'files/ember-cli-build.cjs',
+    ],
   },
 ];
diff --git a/files/.prettierrc.js b/files/.prettierrc.cjs
similarity index 100%
rename from files/.prettierrc.js
rename to files/.prettierrc.cjs
diff --git a/files/.stylelintrc.js b/files/.stylelintrc.cjs
similarity index 100%
rename from files/.stylelintrc.js
rename to files/.stylelintrc.cjs
diff --git a/files/.template-lintrc.js b/files/.template-lintrc.cjs
similarity index 100%
rename from files/.template-lintrc.js
rename to files/.template-lintrc.cjs
diff --git a/files/_js_eslint.config.mjs b/files/_js_eslint.config.mjs
index 7e5a2d6e..feeeb166 100644
--- a/files/_js_eslint.config.mjs
+++ b/files/_js_eslint.config.mjs
@@ -72,16 +72,7 @@ export default [
    * CJS node files
    */
   {
-    files: [
-      '**/*.cjs',
-      'config/**/*.js',
-      'testem.js',
-      'testem*.js',
-      '.prettierrc.js',
-      '.stylelintrc.js',
-      '.template-lintrc.js',
-      'ember-cli-build.js',
-    ],
+    files: ['**/*.cjs'],
     plugins: {
       n,
     },
diff --git a/files/_ts_eslint.config.mjs b/files/_ts_eslint.config.mjs
index 84bb692e..d984dd22 100644
--- a/files/_ts_eslint.config.mjs
+++ b/files/_ts_eslint.config.mjs
@@ -92,16 +92,7 @@ export default ts.config(
    * CJS node files
    */
   {
-    files: [
-      '**/*.cjs',
-      'config/**/*.js',
-      'testem.js',
-      'testem*.js',
-      '.prettierrc.js',
-      '.stylelintrc.js',
-      '.template-lintrc.js',
-      'ember-cli-build.js',
-    ],
+    files: ['**/*.cjs'],
     plugins: {
       n,
     },
diff --git a/files/config/environment.js b/files/config/environment.cjs
similarity index 100%
rename from files/config/environment.js
rename to files/config/environment.cjs
diff --git a/files/config/targets.js b/files/config/targets.cjs
similarity index 100%
rename from files/config/targets.js
rename to files/config/targets.cjs
diff --git a/files/ember-cli-build.js b/files/ember-cli-build.cjs
similarity index 100%
rename from files/ember-cli-build.js
rename to files/ember-cli-build.cjs
diff --git a/files/package.json b/files/package.json
index 1fb4b1a9..05cf6e9b 100644
--- a/files/package.json
+++ b/files/package.json
@@ -4,6 +4,7 @@
   "private": true,
   "description": "Small description for <%= name %> goes here",
   "repository": "",
+  "type": "module",
   "license": "MIT",
   "author": "",
   "directories": {
diff --git a/tests/default.test.mjs b/tests/default.test.mjs
index be3ce7db..de90dbfe 100644
--- a/tests/default.test.mjs
+++ b/tests/default.test.mjs
@@ -93,7 +93,7 @@ describe('basic functionality', function () {
           });
 
           writeFileSync(
-            join(project.dir(), 'testem-dev.js'),
+            join(project.dir(), 'testem-dev.cjs'),
             `module.exports = {
   test_page: 'tests/index.html?hidepassed',
   disable_watching: true,
@@ -115,7 +115,7 @@ describe('basic functionality', function () {
     },
   },
   middleware: [
-    require(__dirname + '/testem-proxy.js')('${appURL}')
+    require(__dirname + '/testem-proxy.cjs')('${appURL}')
   ],
 };
 `,
@@ -124,7 +124,7 @@ describe('basic functionality', function () {
           let testResult = await project.execa('pnpm', [
             'testem',
             '--file',
-            'testem-dev.js',
+            'testem-dev.cjs',
             'ci',
           ]);
           expect(testResult.exitCode).to.eq(0, testResult.output);
diff --git a/tests/fixture-ts/testem-proxy.js b/tests/fixture-ts/testem-proxy.cjs
similarity index 100%
rename from tests/fixture-ts/testem-proxy.js
rename to tests/fixture-ts/testem-proxy.cjs
diff --git a/tests/fixture/testem-proxy.js b/tests/fixture/testem-proxy.cjs
similarity index 100%
rename from tests/fixture/testem-proxy.js
rename to tests/fixture/testem-proxy.cjs