diff --git a/lib/form/modgrade.php b/lib/form/modgrade.php
index 863f1b1db49..410bb17b9e7 100644
--- a/lib/form/modgrade.php
+++ b/lib/form/modgrade.php
@@ -285,10 +285,18 @@ class MoodleQuickForm_modgrade extends MoodleQuickForm_group {
     protected function process_value($type='none', $scale=null, $point=null, $rescalegrades=null) {
         global $COURSE;
         $val = 0;
-        if ($this->isupdate && $this->hasgrades && $this->canrescale && $this->currentgradetype == 'point' && empty($rescalegrades)) {
-            // If the maxgrade field is disabled with javascript, no value is sent with the form and mform assumes the default.
+
+        // If the maxgrade field is disabled with javascript, no value is sent with the form and mform assumes the default.
+        if ($this->isupdate && $this->hasgrades && $this->currentgradetype == 'point') {
+            // If the user cannot rescale, then return the original.
+            $returnoriginal = !$this->canrescale;
+
             // If the user was forced to choose a rescale option - and they haven't - prevent any changes to the max grade.
-            return (string)unformat_float($this->currentgrade);
+            $returnoriginal = $returnoriginal || ($this->canrescale && empty($rescalegrades));
+
+            if ($returnoriginal) {
+                return (string)unformat_float($this->currentgrade);
+            }
         }
         switch ($type) {
             case 'point':