diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index a2dd3e4b394..bf1b7176fd9 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -2371,6 +2371,7 @@ class assign {
         // Submissions are included if all are true:
         //   - The assignment is visible in the gradebook.
         //   - No previous notification has been sent.
+        //   - The grader was a real user, not an automated process.
         //   - If marking workflow is not enabled, the grade was updated in the past 24 hours, or
         //     if marking workflow is enabled, the workflow state is at 'released'.
         $sql = "SELECT g.id as gradeid, a.course, a.name, a.blindmarking, a.revealidentities,
@@ -2384,7 +2385,7 @@ class assign {
             LEFT JOIN {assign_user_mapping} um ON g.id = um.userid AND um.assignment = a.id
                  WHERE ((a.markingworkflow = 0 AND g.timemodified >= :yesterday AND g.timemodified <= :today) OR
                         (a.markingworkflow = 1 AND uf.workflowstate = :wfreleased)) AND
-                       uf.mailed = 0 AND gri.hidden = 0
+                       g.grader > 0 AND uf.mailed = 0 AND gri.hidden = 0
               ORDER BY a.course, cm.id";
 
         $params = array(
@@ -3714,7 +3715,8 @@ class assign {
                 $grade->timemodified = $grade->timecreated;
             }
             $grade->grade = -1;
-            $grade->grader = $USER->id;
+            // Do not set the grader id here as it would be the admin users which is incorrect.
+            $grade->grader = -1;
             if ($attemptnumber >= 0) {
                 $grade->attemptnumber = $attemptnumber;
             }
@@ -5100,8 +5102,10 @@ class assign {
                     $gradefordisplay = $this->display_grade($gradebookgrade->grade, false);
                 }
                 $gradeddate = $gradebookgrade->dategraded;
-                if (isset($grade->grader)) {
+                if (isset($grade->grader) && $grade->grader > 0) {
                     $grader = $DB->get_record('user', array('id' => $grade->grader));
+                } else if (isset($gradebookgrade->usermodified) && $gradebookgrade->usermodified > 0) {
+                    $grader = $DB->get_record('user', array('id' => $gradebookgrade->usermodified));
                 }
             }
 
@@ -5262,10 +5266,12 @@ class assign {
             // First lookup the grader info.
             if (isset($gradercache[$grade->grader])) {
                 $grade->grader = $gradercache[$grade->grader];
-            } else {
+            } else if ($grade->grader > 0) {
                 // Not in cache - need to load the grader record.
                 $grade->grader = $DB->get_record('user', array('id'=>$grade->grader));
-                $gradercache[$grade->grader->id] = $grade->grader;
+                if ($grade->grader) {
+                    $gradercache[$grade->grader->id] = $grade->grader;
+                }
             }
 
             // Now get the gradefordisplay.
diff --git a/mod/assign/tests/locallib_test.php b/mod/assign/tests/locallib_test.php
index d4b17e9a7b8..13e0bd6c552 100644
--- a/mod/assign/tests/locallib_test.php
+++ b/mod/assign/tests/locallib_test.php
@@ -3887,6 +3887,7 @@ Anchor link 2:<a title=\"bananas\" href=\"../logo-240x60.gif\">Link text</a>
         $assign->get_user_grade($student->id, true);
 
         // Set the grade to something errant.
+        // We don't set the grader here, so we expect it to be -1 as a result.
         $DB->set_field(
             'assign_grades',
             'grade',
@@ -3904,6 +3905,7 @@ Anchor link 2:<a title=\"bananas\" href=\"../logo-240x60.gif\">Link text</a>
         // Check that the gradebook was updated with the assign grade. So we can guarentee test results later on.
         $expectedgrade = $grade == -1 ? null : $grade; // Assign sends null to the gradebook for -1 grades.
         $gradegrade = grade_grade::fetch(array('userid' => $student->id, 'itemid' => $assign->get_grade_item()->id));
+        $this->assertEquals(-1, $gradegrade->usermodified);
         $this->assertEquals($expectedgrade, $gradegrade->rawgrade);
 
         // Call fix_null_grades().
@@ -3915,6 +3917,9 @@ Anchor link 2:<a title=\"bananas\" href=\"../logo-240x60.gif\">Link text</a>
 
         $gradegrade = grade_grade::fetch(array('userid' => $student->id, 'itemid' => $assign->get_grade_item()->id));
 
+        $this->assertEquals(-1, $gradegrade->usermodified);
+        $this->assertEquals($gradebookvalue, $gradegrade->finalgrade);
+
         // Check that the grade was updated in the gradebook by fix_null_grades.
         $this->assertEquals($gradebookvalue, $gradegrade->finalgrade);
     }