diff --git a/lib/phpunit/classes/base_testcase.php b/lib/phpunit/classes/base_testcase.php
index 231ce1f4198..fcb8786eaa4 100644
--- a/lib/phpunit/classes/base_testcase.php
+++ b/lib/phpunit/classes/base_testcase.php
@@ -242,7 +242,7 @@ abstract class base_testcase extends PHPUnit_Framework_TestCase {
                         }
                     } // match by exact string
                     else {
-                        if ($node->getAttribute($name) != $value) {
+                        if ($node->getAttribute($name) !== (string) $value) {
                             $invalid = true;
                         }
                     }
diff --git a/question/behaviour/manualgraded/tests/walkthrough_test.php b/question/behaviour/manualgraded/tests/walkthrough_test.php
index d63030c9248..c47e2053e1b 100644
--- a/question/behaviour/manualgraded/tests/walkthrough_test.php
+++ b/question/behaviour/manualgraded/tests/walkthrough_test.php
@@ -18,8 +18,7 @@
  * This file contains tests that walks a question through the manual graded
  * behaviour.
  *
- * @package    qbehaviour
- * @subpackage manualgraded
+ * @package    qbehaviour_manualgraded
  * @copyright  2009 The Open University
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
@@ -622,4 +621,40 @@ class qbehaviour_manualgraded_walkthrough_testcase extends qbehaviour_walkthroug
             new question_pattern_expectation($preg)
         );
     }
+
+    public function test_manual_grading_reshows_exactly_the_mark_input() {
+        global $PAGE;
+
+        // The current text editor depends on the users profile setting - so it needs a valid user.
+        $this->setAdminUser();
+        // Required to init a text editor.
+        $PAGE->set_url('/');
+
+        // Create an essay question graded out of 15 and attempt it.
+        $essay = test_question_maker::make_an_essay_question();
+        $this->start_attempt_at_question($essay, 'deferredfeedback', 15);
+        $this->process_submission(array('answer' => 'This is my wonderful essay!', 'answerformat' => FORMAT_HTML));
+        $this->quba->finish_all_questions();
+
+        // Verify.
+        $this->check_current_state(question_state::$needsgrading);
+        $this->check_current_mark(null);
+        $this->assertEquals('This is my wonderful essay!',
+                $this->quba->get_response_summary($this->slot));
+
+        // Try to process a grade where the score will be stored rounded.
+        $this->manual_grade('Comment', '5.0', FORMAT_HTML);
+
+        // Verify.
+        $this->check_current_state(question_state::$mangrpartial);
+        $this->check_current_mark(5);
+        $this->displayoptions->manualcomment = question_display_options::EDITABLE;
+        $this->render();
+        $this->check_output_contains_text_input('-mark', '5.0');
+
+        // Rescale what the question is worth, and verify the display.
+        $this->get_question_attempt()->set_max_mark(1);
+        $this->render();
+        $this->check_output_contains_text_input('-mark', '0.3333333');
+    }
 }
diff --git a/question/behaviour/rendererbase.php b/question/behaviour/rendererbase.php
index ea6a1878afe..b47488726e5 100644
--- a/question/behaviour/rendererbase.php
+++ b/question/behaviour/rendererbase.php
@@ -126,9 +126,6 @@ abstract class qbehaviour_renderer extends plugin_renderer_base {
             if (!is_null($currentmark)) {
                 $attributes['value'] = $currentmark;
             }
-            $a = new stdClass();
-            $a->max = $qa->format_max_mark($options->markdp);
-            $a->mark = html_writer::empty_tag('input', $attributes);
 
             $markrange = html_writer::empty_tag('input', array(
                 'type' => 'hidden',
@@ -152,6 +149,9 @@ abstract class qbehaviour_renderer extends plugin_renderer_base {
                         array('class' => 'error')) . html_writer::empty_tag('br');
             }
 
+            $a = new stdClass();
+            $a->max = $qa->format_max_mark($options->markdp);
+            $a->mark = html_writer::empty_tag('input', $attributes);
             $mark = html_writer::tag('div', html_writer::tag('div',
                         html_writer::tag('label', get_string('mark', 'question'),
                         array('for' => $markfield)),
diff --git a/question/engine/questionattempt.php b/question/engine/questionattempt.php
index fa110dde2ae..d295170e3d3 100644
--- a/question/engine/questionattempt.php
+++ b/question/engine/questionattempt.php
@@ -649,17 +649,29 @@ class question_attempt {
 
     /**
      * This is used by the manual grading code, particularly in association with
-     * validation. If there is a mark submitted in the request, then use that,
-     * otherwise use the latest mark for this question.
-     * @return number the current manual mark for this question, formatted for display.
+     * validation. It gets the current manual mark for a question, in exactly the string
+     * form that the teacher entered it, if possible. This may come from the current
+     * POST request, if there is one, otherwise from the database.
+     *
+     * @return string the current manual mark for this question, in the format the teacher typed,
+     *     if possible.
      */
     public function get_current_manual_mark() {
+        // Is there a current value in the current POST data? If so, use that.
         $mark = $this->get_submitted_var($this->get_behaviour_field_name('mark'), PARAM_RAW_TRIMMED);
-        if (is_null($mark)) {
-            return format_float($this->get_mark(), 7, true, true);
-        } else {
+        if ($mark !== null) {
             return $mark;
         }
+
+        // Otherwise, use the stored value.
+        // If the question max mark has not changed, use the stored value that was input.
+        $storedmaxmark = $this->get_last_behaviour_var('maxmark');
+        if ($storedmaxmark !== null && ($storedmaxmark - $this->get_max_mark()) < 0.0000005) {
+            return $this->get_last_behaviour_var('mark');
+        }
+
+        // The max mark for this question has changed so we must re-scale the current mark.
+        return format_float($this->get_mark(), 7, true, true);
     }
 
     /**