diff --git a/addressbook/inc/class.addressbook_bo.inc.php b/addressbook/inc/class.addressbook_bo.inc.php
index 8bb590ffd2..a7278877c5 100755
--- a/addressbook/inc/class.addressbook_bo.inc.php
+++ b/addressbook/inc/class.addressbook_bo.inc.php
@@ -320,7 +320,7 @@ class addressbook_bo extends addressbook_so
 	 * @param array $prefs addressbook preferences
 	 * @return boolean
 	 */
-	public static function private_addressbook($contact_repository, array $prefs)
+	public static function private_addressbook($contact_repository, array $prefs=null)
 	{
 		return $contact_repository == 'sql' && $prefs['private_addressbook'];
 	}