diff --git a/term_reference_filter_by_views.module b/term_reference_filter_by_views.module
index a544f97..9371b39 100644
--- a/term_reference_filter_by_views.module
+++ b/term_reference_filter_by_views.module
@@ -28,10 +28,14 @@ function term_reference_filter_by_views_field_widget_form_alter(&$element, &$for
           $allowed[$tid] = preg_replace('/\s\s+/', ' ', str_replace("\n", '', trim(decode_entities(strip_tags($row)))));
         }
         */
-        if (!empty($allowed)) {
-          $options = array();
-          $options = array_intersect_key($allowed, $element['#options']);
-          $element['#options'] = $options;
+        $options = array();
+        $options = array_intersect_key($element['#options'], $allowed);
+        $element['#options'] = $options;
+        if ($element['#type'] == 'select') {
+            $element['#options'] = _term_reference_filter_by_views_array_unshift_assoc($element['#options'], '', t('- None -'));
+        }
+        elseif ($element['#type'] == 'radios') {
+            $element['#options'] = _term_reference_filter_by_views_array_unshift_assoc($element['#options'], '', t('n/a'));
         }
       }
       // for Widgets that uses Autocomplete
@@ -169,7 +173,7 @@ function term_reference_filter_by_views_form_field_ui_field_edit_form_alter(&$fo
         '#element_validate' => array('_element_validate_integer_positive'),
       );
       if (!empty($view_settings['view_name']) && isset($form['instance']['widget']['settings']['autocomplete_match'])) {
-        $form['instance']['widget']['settings']['autocomplete_match']['#access'] = FALSE;
+        $form['instance']['widget']['settings']['autocomplete_match']['#access'] = FALSE;
       }
     }
     else {
@@ -337,6 +341,15 @@ function term_reference_filter_by_views_views_api() {
 function term_reference_filter_by_views_views_plugins_alter(&$plugins) {
   // Change the handler for references dialog.
   if (isset($plugins['display']['references_dialog'])) {
-    $plugins['display']['references_dialog']['handler'] = 'term_reference_references_dialog_plugin_display';
+    $plugins['display']['references_dialog']['handler'] = 'term_reference_references_dialog_plugin_display';
   }
-}
\ No newline at end of file
+}
+
+/**
+ * Array unshift associative
+ */
+function _term_reference_filter_by_views_array_unshift_assoc(&$arr, $key, $val)  {
+  $arr = array_reverse($arr, TRUE);
+  $arr[$key] = $val;
+  return array_reverse($arr, TRUE);
+}