diff --git a/lib/grade/grade_item.php b/lib/grade/grade_item.php
index 8b1d3122f08..12afe84e393 100644
--- a/lib/grade/grade_item.php
+++ b/lib/grade/grade_item.php
@@ -742,7 +742,8 @@ class grade_item extends grade_object {
 
             // Standardise score to the new grade range
             // NOTE: this is not compatible with current assignment grading
-            if ($this->itemmodule != 'assignment' and ($rawmin != $this->grademin or $rawmax != $this->grademax)) {
+            $isassignmentmodule = ($this->itemmodule == 'assignment') || ($this->itemmodule == 'assign');
+            if (!$isassignmentmodule && ($rawmin != $this->grademin or $rawmax != $this->grademax)) {
                 $rawgrade = grade_grade::standardise_score($rawgrade, $rawmin, $rawmax, $this->grademin, $this->grademax);
             }
 
diff --git a/mod/assign/lang/en/assign.php b/mod/assign/lang/en/assign.php
index 5b2438b1e26..96c1c22de69 100644
--- a/mod/assign/lang/en/assign.php
+++ b/mod/assign/lang/en/assign.php
@@ -64,6 +64,7 @@ $string['batchoperationconfirmreverttodraft'] = 'Revert selected submissions to
 $string['batchoperationlock'] = 'lock submissions';
 $string['batchoperationunlock'] = 'unlock submissions';
 $string['batchoperationreverttodraft'] = 'revert submissions to draft';
+$string['changegradewarning'] = 'This assignment has graded submissions and changing the grade will not automatically re-calculate existing submission grades. You must re-grade all existing submissions, if you wish to change the grade.';
 $string['comment'] = 'Comment';
 $string['conversionexception'] = 'Could not convert assignment. Exception was: {$a}.';
 $string['configshowrecentsubmissions'] = 'Everyone can see notifications of submissions in recent activity reports.';
diff --git a/mod/assign/mod_form.php b/mod/assign/mod_form.php
index 8ad624c238b..4b9929f6048 100644
--- a/mod/assign/mod_form.php
+++ b/mod/assign/mod_form.php
@@ -45,7 +45,7 @@ class mod_assign_mod_form extends moodleform_mod {
      * @return void
      */
     function definition() {
-        global $CFG, $DB;
+        global $CFG, $DB, $PAGE;
         $mform = $this->_form;
 
         $mform->addElement('header', 'general', get_string('general', 'form'));
@@ -109,6 +109,21 @@ class mod_assign_mod_form extends moodleform_mod {
         $this->standard_coursemodule_elements();
 
         $this->add_action_buttons();
+
+        // Add warning popup/noscript tag, if grades are changed by user.
+        if ($mform->elementExists('grade') && !empty($this->_instance) && $DB->record_exists_select('assign_grades', 'assignment = ? AND grade <> -1', array($this->_instance))) {
+            $module = array(
+                'name' => 'mod_assign',
+                'fullpath' => '/mod/assign/module.js',
+                'requires' => array('node', 'event'),
+                'strings' => array(array('changegradewarning', 'mod_assign'))
+                );
+            $PAGE->requires->js_init_call('M.mod_assign.init_grade_change', null, false, $module);
+
+            // Add noscript tag in case
+            $noscriptwarning = $mform->createElement('static', 'warning', null,  html_writer::tag('noscript', get_string('changegradewarning', 'mod_assign')));
+            $mform->insertElementBefore($noscriptwarning, 'grade');
+        }
     }
 
     /**
diff --git a/mod/assign/module.js b/mod/assign/module.js
index d01c9b30318..a1cbe079237 100644
--- a/mod/assign/module.js
+++ b/mod/assign/module.js
@@ -127,4 +127,16 @@ M.mod_assign.init_grading_options = function(Y) {
             });
         }
     });
+};
+
+M.mod_assign.init_grade_change = function(Y) {
+    var gradenode = Y.one('#id_grade');
+    if (gradenode) {
+        var originalvalue = gradenode.get('value');
+        gradenode.on('change', function() {
+            if (gradenode.get('value') != originalvalue) {
+                alert(M.str.mod_assign.changegradewarning);
+            }
+        });
+    }
 };
\ No newline at end of file