diff --git a/question/type/numerical/db/upgrade.php b/question/type/numerical/db/upgrade.php
index 84f2047f2e6..327cbcbb8e7 100644
--- a/question/type/numerical/db/upgrade.php
+++ b/question/type/numerical/db/upgrade.php
@@ -120,7 +120,7 @@ function xmldb_qtype_numerical_upgrade($oldversion) {
                        qnu.unit AS defaultunit
 
                   FROM {question} q
-                  FROM {question_categories} qc ON qc.id = q.category
+                  JOIN {question_categories} qc ON qc.id = q.category
                   JOIN {question_numerical_options} qno ON qno.question = q.id
                   JOIN {question_numerical_units} qnu ON qnu.id = (
                             SELECT min(id)
diff --git a/question/type/numerical/lang/en/qtype_numerical.php b/question/type/numerical/lang/en/qtype_numerical.php
index abe1c0600b9..ebaf7ce52d9 100644
--- a/question/type/numerical/lang/en/qtype_numerical.php
+++ b/question/type/numerical/lang/en/qtype_numerical.php
@@ -76,6 +76,7 @@ $string['unitchoice'] = 'a multiple choice selection';
 $string['unitedit'] = 'Edit unit';
 $string['unitgraded'] = 'The unit must be given, and will be graded.';
 $string['unithdr'] = 'Unit {$a}';
+$string['unitincorrect'] = 'You did not give the correct unit.';
 $string['unitmandatory'] = 'Mandatory';
 $string['unitmandatory_help'] = '
 
@@ -92,7 +93,6 @@ $string['unitoptional_help'] = '
 * If the unit is badly written or unknown, the response will be considered as non valid.
 ';
 $string['unitnotvalid'] = ' Unit not valid with this numerical value';
-$string['unitunknown'] = ' Undefined unit ';
 $string['unitpenalty'] = 'Unit penalty';
 $string['unitpenalty_help'] = 'The penalty is applied if
 
diff --git a/question/type/numerical/question.php b/question/type/numerical/question.php
index 60453ea6102..9c6210ee8b2 100644
--- a/question/type/numerical/question.php
+++ b/question/type/numerical/question.php
@@ -155,7 +155,7 @@ class qtype_numerical_question extends question_graded_automatically {
         return null;
     }
 
-    protected function apply_unit_penalty($fraction, $unit) {
+    public function apply_unit_penalty($fraction, $unit) {
         if (!empty($unit) && $this->ap->is_known_unit($unit)) {
             return $fraction;
         }
diff --git a/question/type/numerical/questiontype.php b/question/type/numerical/questiontype.php
index a3cf6f8426e..44708eb09d4 100644
--- a/question/type/numerical/questiontype.php
+++ b/question/type/numerical/questiontype.php
@@ -363,16 +363,16 @@ class qtype_numerical extends question_type {
     }
 
     protected function make_answer_processor($units, $unitsleft) {
-        if (empty($questiondata->options->units)) {
+        if (empty($units)) {
             return new qtype_numerical_answer_processor(array());
         }
 
-        $units = array();
-        foreach ($questiondata->options->units as $unit) {
-            $units[$unit->unit] = $unit->multiplier;
+        $cleanedunits = array();
+        foreach ($units as $unit) {
+            $cleanedunits[$unit->unit] = $unit->multiplier;
         }
 
-        return new qtype_numerical_answer_processor($units, $questiondata->options->unitsleft);
+        return new qtype_numerical_answer_processor($cleanedunits, $unitsleft);
     }
 
     function delete_question($questionid, $contextid) {
diff --git a/question/type/numerical/renderer.php b/question/type/numerical/renderer.php
index a0ccec77f7d..cac0543cc85 100644
--- a/question/type/numerical/renderer.php
+++ b/question/type/numerical/renderer.php
@@ -56,7 +56,7 @@ class qtype_numerical_renderer extends qtype_renderer {
             list($value, $unit) = $question->ap->apply_units($currentanswer);
             $answer = $question->get_matching_answer($value);
             if ($answer) {
-                $fraction = $answer->fraction;
+                $fraction = $question->apply_unit_penalty($answer->fraction, $unit);
             } else {
                 $fraction = 0;
             }
@@ -101,12 +101,19 @@ class qtype_numerical_renderer extends qtype_renderer {
 
         list($value, $unit) = $question->ap->apply_units($qa->get_last_qt_var('answer'));
         $answer = $question->get_matching_answer($value);
-        if (!$answer || !$answer->feedback) {
-            return '';
+
+        if ($answer && $answer->feedback) {
+            $feedback = $question->format_text($answer->feedback, $answer->feedbackformat,
+                    $qa, 'question', 'answerfeedback', $answer->id);
+        } else {
+            $feedback = '';
         }
 
-        return $question->format_text($answer->feedback, $answer->feedbackformat,
-                $qa, 'question', 'answerfeedback', $answer->id);
+        if ($question->unitgradingtype && !$question->ap->is_known_unit($unit)) {
+            $feedback .= html_writer::tag('p', get_string('unitincorrect', 'qtype_numerical'));
+        }
+
+        return $feedback;
     }
 
     public function correct_response(question_attempt $qa) {