diff --git a/main/survey/preview.php b/main/survey/preview.php
index 804e9239ab..86e0641f86 100755
--- a/main/survey/preview.php
+++ b/main/survey/preview.php
@@ -203,7 +203,7 @@ if (api_is_course_admin() ||
     }
 
     $before = 0;
-    if (isset($paged_questions[$_GET['show'] -1])) {
+    if (isset($_GET['show']) && isset($paged_questions[$_GET['show'] -1])) {
         $before = count($paged_questions[$_GET['show'] -1]);
     }