diff --git a/packages/cli/lib/lib/webpack/webpack-server-config.js b/packages/cli/lib/lib/webpack/webpack-server-config.js
index 7da458e2a..22ec1f6fc 100644
--- a/packages/cli/lib/lib/webpack/webpack-server-config.js
+++ b/packages/cli/lib/lib/webpack/webpack-server-config.js
@@ -5,7 +5,7 @@ const baseConfig = require('./webpack-base-config');
 function serverConfig(env) {
 	return {
 		entry: {
-			'ssr-bundle': env.source('index.js'),
+			'ssr-bundle': env.source('index'),
 		},
 		output: {
 			publicPath: '/',