diff --git a/www/backup.php b/www/backup.php
index fa9b9bb45..1c5cd6be6 100644
--- a/www/backup.php
+++ b/www/backup.php
@@ -1970,7 +1970,7 @@ function BackupDirectionChanged() {
 
             var activeTabNumber =
 <?php
-    if (isset($_GET['tab']))
+    if (isset($_GET['tab']) and is_numeric($_GET['tab']))
         print $_GET['tab'];
     else
         print "0";