diff --git a/www/tilt.php b/www/tilt.php
index 51c8811..450ecb6 100644
--- a/www/tilt.php
+++ b/www/tilt.php
@@ -1,5 +1,5 @@
 <?php
-	$output = shell_exec('/home/pi/servo-pi/drive-servo.py 1 ' . $_GET['position']);
+	$output = shell_exec('/home/pi/servo-pi/drive-servo.py 1 ' . escapeshellarg($_GET['position']));
 	// 2>&1
 ?>