diff --git a/question/classes/statistics/responses/analysis_for_class.php b/question/classes/statistics/responses/analysis_for_class.php
index 9c83fa13bc2..57ef4745c7e 100644
--- a/question/classes/statistics/responses/analysis_for_class.php
+++ b/question/classes/statistics/responses/analysis_for_class.php
@@ -107,7 +107,7 @@ class analysis_for_class {
             return true;
         } else if (count($this->actualresponses) == 1) {
             $onlyactualresponse = reset($this->actualresponses);
-            return !$onlyactualresponse->response_matches($this->modelresponse);
+            return (string)$onlyactualresponse != $this->modelresponse;
         }
         return false;
     }
diff --git a/question/type/numerical/question.php b/question/type/numerical/question.php
index 8df2ce93486..c86f2fffc54 100644
--- a/question/type/numerical/question.php
+++ b/question/type/numerical/question.php
@@ -249,7 +249,7 @@ class qtype_numerical_question extends question_graded_automatically {
     }
 
     public function classify_response(array $response) {
-        if (empty($response['answer'])) {
+        if (!$this->is_gradable_response($response)) {
             return array($this->id => question_classified_response::no_response());
         }
 
diff --git a/question/type/numerical/tests/question_test.php b/question/type/numerical/tests/question_test.php
index 84fc7d0d7c4..6769864a71f 100644
--- a/question/type/numerical/tests/question_test.php
+++ b/question/type/numerical/tests/question_test.php
@@ -211,6 +211,9 @@ class qtype_numerical_question_test extends advanced_testcase {
         $this->assertEquals(array(
                 new question_classified_response(17, '42', 0.0)),
                 $num->classify_response(array('answer' => '42')));
+        $this->assertEquals(array(
+                new question_classified_response(17, '0', 0.0)),
+                $num->classify_response(array('answer' => '0')));
         $this->assertEquals(array(
                 new question_classified_response(13, '3.14', 1.0)),
                 $num->classify_response(array('answer' => '3.14')));
@@ -230,6 +233,9 @@ class qtype_numerical_question_test extends advanced_testcase {
         $this->assertEquals(array(
                 new question_classified_response(0, '42', 0.0)),
                 $num->classify_response(array('answer' => '42')));
+        $this->assertEquals(array(
+                new question_classified_response(0, '0', 0.0)),
+                $num->classify_response(array('answer' => '0')));
         $this->assertEquals(array(
                 question_classified_response::no_response()),
                 $num->classify_response(array('answer' => '')));
@@ -292,4 +298,4 @@ class qtype_numerical_question_test extends advanced_testcase {
                 new question_classified_response(13, '1 332', 0.8)),
                 $num->classify_response(array('answer' => '1 332')));
     }
-}
\ No newline at end of file
+}