diff --git a/core/js/files/iedavclient.js b/core/js/files/iedavclient.js
index 9e83f5b9a2..a0185fb3be 100644
--- a/core/js/files/iedavclient.js
+++ b/core/js/files/iedavclient.js
@@ -29,6 +29,7 @@
 
 			var self = this;
 			var xhr = this.xhrProvider();
+			headers = headers || {};
 
 			if (this.userName) {
 				headers['Authorization'] = 'Basic ' + btoa(this.userName + ':' + this.password);