diff --git a/lib/Server.js b/lib/Server.js
index 7a73c1ca20..f0f21630ab 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -50,7 +50,7 @@ function Server(compiler, options) {
   this.allowedHosts = options.allowedHosts;
   this.sockets = [];
   this.contentBaseWatchers = [];
-  this.watchOptions = options.watchOptions;
+  this.watchOptions = options.watchOptions || {};
 
   // Listening for events
   const invalidPlugin = () => {