diff --git a/include/ajax.tickets.php b/include/ajax.tickets.php
index 9d5169dbd56020c34b3374c90d4fb1ac77a63a47..b613144f4e2eaea7cb925b247d121639c69ec489 100644
--- a/include/ajax.tickets.php
+++ b/include/ajax.tickets.php
@@ -263,7 +263,7 @@ class TicketsAjaxAPI extends AjaxController {
     function acquireLock($tid) {
         global $cfg,$thisstaff;
 
-        if(!$tid or !is_numeric($tid) or !$thisstaff or !$cfg or !$cfg->getLockTime())
+        if(!$tid || !is_numeric($tid) || !$thisstaff || !$cfg || !$cfg->getLockTime())
             return 0;
 
         if(!($ticket = Ticket::lookup($tid)) || !$ticket->checkStaffAccess($thisstaff))
@@ -290,10 +290,10 @@ class TicketsAjaxAPI extends AjaxController {
     function renewLock($tid, $id) {
         global $thisstaff;
 
-        if(!$id or !is_numeric($id) or !$thisstaff)
+        if(!$tid || !is_numeric($tid) || !$id || !is_numeric($id) || !$thisstaff)
             return $this->json_encode(array('id'=>0, 'retry'=>true));
 
-        $lock= TicketLock::lookup($id);
+        $lock= TicketLock::lookup($id, $tid);
         if(!$lock || !$lock->getStaffId() || $lock->isExpired()) //Said lock doesn't exist or is is expired
             return self::acquireLock($tid); //acquire the lock
 
diff --git a/include/mysqli.php b/include/mysqli.php
index 7245d9ec20eeab75197500a8b9f5d8f06af8e567..3b535919e88f18fec8465067c7f7b55d7b4e54f2 100644
--- a/include/mysqli.php
+++ b/include/mysqli.php
@@ -160,7 +160,7 @@ function db_result($res, $row=0) {
     return $value;
 }
 
-function db_fetch_array($res, $mode=MYSQL_ASSOC) {
+function db_fetch_array($res, $mode=MYSQLI_ASSOC) {
     return ($res) ? db_output($res->fetch_array($mode)) : NULL;
 }