diff --git a/test-app/.try.mjs b/test-app/.try.mjs
index 7acc66f..ac98e56 100644
--- a/test-app/.try.mjs
+++ b/test-app/.try.mjs
@@ -1,6 +1,6 @@
 // When building your addon for older Ember versions you need to have the required files
 const compatFiles = {
-  'ember-cli-build.js': `const EmberApp = require('ember-cli/lib/broccoli/ember-app');
+  'ember-cli-build.cjs': `const EmberApp = require('ember-cli/lib/broccoli/ember-app');
 const { compatBuild } = require('@embroider/compat');
 module.exports = async function (defaults) {
   const { buildOnce } = await import('@embroider/vite');
diff --git a/test-app/vite.config.mjs b/test-app/vite.config.mjs
index 5401cd2..417b5fb 100644
--- a/test-app/vite.config.mjs
+++ b/test-app/vite.config.mjs
@@ -1,10 +1,10 @@
 import { defineConfig } from 'vite';
-import { extensions, ember, hbs } from '@embroider/vite';
+import { extensions, ember, hbs, classicEmberSupport } from '@embroider/vite';
 import { babel } from '@rollup/plugin-babel';
 
 export default defineConfig({
   plugins: [
-    hbs(),
+    ...(process.env.ENABLE_COMPAT_BUILD ? [classicEmberSupport()] : [hbs()]),
     ember(),
     babel({
       babelHelpers: 'runtime',