diff --git a/core/authentication/resources/classes/authentication.php b/core/authentication/resources/classes/authentication.php
index a287b927ed..81c0a9c569 100644
--- a/core/authentication/resources/classes/authentication.php
+++ b/core/authentication/resources/classes/authentication.php
@@ -420,7 +420,7 @@ class authentication {
 			}
 
 		//remote port number from the domain name
-			$domain_array = explode(":", $domain_name);
+			$domain_array = explode(":", $this->domain_name);
 			if (count($domain_array) > 1) {
 				$domain_name = $domain_array[0];
 			}