diff --git a/lib/server.js b/lib/server.js
index 3fbee3e07..6d998e8fb 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -102,12 +102,8 @@ Server.prototype.init = function () {
 
   if (this.ws) this.ws.close();
 
-  var wsModule;
-  switch (this.wsEngine) {
-    case 'uws': wsModule = require('uws'); break;
-    case 'ws': wsModule = require('ws'); break;
-    default: throw new Error('unknown wsEngine');
-  }
+  // add explicit require for bundlers like webpack
+  var wsModule = this.wsEngine === 'ws' ? require('ws') : require(this.wsEngine);
   this.ws = new wsModule.Server({
     noServer: true,
     clientTracking: false,