diff --git a/lib/core/renderer.js b/lib/core/renderer.js
index 14bbea5482..0bdef1ab06 100644
--- a/lib/core/renderer.js
+++ b/lib/core/renderer.js
@@ -3,7 +3,6 @@ import serialize from 'serialize-javascript'
 import generateETag from 'etag'
 import fresh from 'fresh'
 import Tapable from 'tappable'
-import pify from 'pify'
 import serveStatic from 'serve-static'
 import compression from 'compression'
 import _ from 'lodash'
@@ -167,9 +166,6 @@ export default class Renderer extends Tapable {
       runInNewContext: false,
       basedir: this.options.rootDir
     }, this.options.render.bundleRenderer))
-
-    // Promisify renderToString
-    this.bundleRenderer.renderToString = pify(this.bundleRenderer.renderToString)
   }
 
   useMiddleware (m) {