diff --git a/grade/report/grader/module.js b/grade/report/grader/module.js
index 54af5487bfb..8d5f0906d79 100644
--- a/grade/report/grader/module.js
+++ b/grade/report/grader/module.js
@@ -741,9 +741,11 @@ M.gradereport_grader.classes.existingfield = function(ajax, userid, itemid) {
     this.editfeedback = ajax.showquickfeedback;
     this.grade = this.report.Y.one('#grade_'+userid+'_'+itemid);
 
-    for(var i = 0; i < this.report.grades.length; i++) {
-        if (this.report.grades[i]['user']==this.userid && this.report.grades[i]['item']==this.itemid) {
-            this.oldgrade = this.report.grades[i]['grade'];
+    if (this.report.grades) {
+        for (var i = 0; i < this.report.grades.length; i++) {
+            if (this.report.grades[i]['user']==this.userid && this.report.grades[i]['item']==this.itemid) {
+                this.oldgrade = this.report.grades[i]['grade'];
+            }
         }
     }