diff --git a/mod/choice/lang/en/choice.php b/mod/choice/lang/en/choice.php
index e977d97e1d1..d7d4df09a59 100644
--- a/mod/choice/lang/en/choice.php
+++ b/mod/choice/lang/en/choice.php
@@ -28,6 +28,7 @@ $string['allowupdate'] = 'Allow choice to be updated';
 $string['allowmultiple'] = 'Allow more than one choice to be selected';
 $string['answered'] = 'Answered';
 $string['cannotsubmit'] = 'Sorry, there was a problem submitting your choice. Please try again.';
+$string['closebeforeopen'] = 'You have specified a close date before the open date.';
 $string['completionsubmit'] = 'Show as complete when user makes a choice';
 $string['displayhorizontal'] = 'Display horizontally';
 $string['displaymode'] = 'Display mode for the options';
diff --git a/mod/choice/mod_form.php b/mod/choice/mod_form.php
index 756a79b1123..e15ad2df714 100644
--- a/mod/choice/mod_form.php
+++ b/mod/choice/mod_form.php
@@ -139,6 +139,25 @@ class mod_choice_mod_form extends moodleform_mod {
         return $data;
     }
 
+    /**
+     * Enforce validation rules here
+     *
+     * @param array $data array of ("fieldname"=>value) of submitted data
+     * @param array $files array of uploaded files "element_name"=>tmp_file_path
+     * @return array
+     **/
+    public function validation($data, $files) {
+        $errors = parent::validation($data, $files);
+
+        // Check open and close times are consistent.
+        if ($data['timeopen'] && $data['timeclose'] &&
+                $data['timeclose'] < $data['timeopen']) {
+            $errors['timeclose'] = get_string('closebeforeopen', 'choice');
+        }
+
+        return $errors;
+    }
+
     function add_completion_rules() {
         $mform =& $this->_form;