diff --git a/addressbook/inc/class.addressbook_ldap.inc.php b/addressbook/inc/class.addressbook_ldap.inc.php
index c304103007..888345be52 100644
--- a/addressbook/inc/class.addressbook_ldap.inc.php
+++ b/addressbook/inc/class.addressbook_ldap.inc.php
@@ -920,7 +920,7 @@ class addressbook_ldap
 
 				case 'id':
 				case 'contact_id':
-					$filter .= $this->ids_filter($value);
+					$filters .= $this->ids_filter($value);
 					break;
 
 				default: