diff --git a/question/type/edit_question_form.php b/question/type/edit_question_form.php
index a211b31d7ae60..b93e46ae4a558 100644
--- a/question/type/edit_question_form.php
+++ b/question/type/edit_question_form.php
@@ -656,7 +656,7 @@ public function validation($fromform, $files) {
         }
 
         // Default mark.
-        if ($fromform['defaultmark'] < 0) {
+        if (array_key_exists('defaultmark', $fromform) && $fromform['defaultmark'] < 0) {
             $errors['defaultmark'] = get_string('defaultmarkmustbepositive', 'question');
         }