diff --git a/grade/report/grader/lib.php b/grade/report/grader/lib.php
index b69e31022ac..c4b6e63e8fa 100644
--- a/grade/report/grader/lib.php
+++ b/grade/report/grader/lib.php
@@ -448,22 +448,22 @@ class grade_report_grader extends grade_report {
                     $this->groupwheresql_params, $enrolledparams, $relatedctxparams);
 
             $sortjoin = "LEFT JOIN {grade_grades} g ON g.userid = u.id AND g.itemid = $this->sortitemid";
-            $sort = "g.finalgrade $this->sortorder";
+            $sort = "g.finalgrade $this->sortorder, u.idnumber, u.lastname, u.firstname, u.email";
         } else {
             $sortjoin = '';
             switch($this->sortitemid) {
                 case 'lastname':
-                    $sort = "u.lastname $this->sortorder, u.firstname $this->sortorder";
+                    $sort = "u.lastname $this->sortorder, u.firstname $this->sortorder, u.idnumber, u.email";
                     break;
                 case 'firstname':
-                    $sort = "u.firstname $this->sortorder, u.lastname $this->sortorder";
+                    $sort = "u.firstname $this->sortorder, u.lastname $this->sortorder, u.idnumber, u.email";
                     break;
                 case 'email':
-                    $sort = "u.email $this->sortorder";
+                    $sort = "u.email $this->sortorder, u.firstname, u.lastname, u.idnumber";
                     break;
                 case 'idnumber':
                 default:
-                    $sort = "u.idnumber $this->sortorder";
+                    $sort = "u.idnumber $this->sortorder, u.firstname, u.lastname, u.email";
                     break;
             }