--- a/trip.php
+++ b/trip.php
@@ -1,12 +1,9 @@
 <?php
 include ('include/common.inc.php');
-$tripid = filter_var($_REQUEST['tripid'], FILTER_SANITIZE_NUMBER_INT);
-$stopid = filter_var($_REQUEST['stopid'], FILTER_SANITIZE_NUMBER_INT);
-$routeid = filter_var($_REQUEST['routeid'], FILTER_SANITIZE_NUMBER_INT);
 
 $routetrips = Array();
 
-if ($_REQUEST['routeid'] && !$_REQUEST['tripid']) {
+if (isset($routeid) && !isset($tripid)) {
     $trip = getRouteNextTrip($routeid);
     $tripid = $trip['trip_id'];
 } else {