diff --git a/mod/assignment/type/online/assignment.class.php b/mod/assignment/type/online/assignment.class.php
index d7052cb3d5a..097ffffb7be 100644
--- a/mod/assignment/type/online/assignment.class.php
+++ b/mod/assignment/type/online/assignment.class.php
@@ -19,6 +19,10 @@ class assignment_online extends assignment_base {
         $editmode = ($editable && !empty($_GET['edit']));
 
         if ($editmode) {
+            //guest can not edit or submit assignment
+            if (isguest($USER->id)) {
+                 error(get_string('guestnosubmit', 'assignment'));
+            }
             $this->view_header(get_string('editmysubmission', 'assignment'));
         } else {
             $this->view_header();