diff --git a/src/datetime.js b/src/datetime.js
index 902790945..18ee4d21a 100644
--- a/src/datetime.js
+++ b/src/datetime.js
@@ -432,7 +432,7 @@ export default class DateTime {
   /**
    * @access private
    */
-  constructor(config) {
+  constructor(config = {}) {
     const zone = config.zone || Settings.defaultZone;
 
     let invalid =