diff --git a/term_reference_tree.module b/term_reference_tree.module
index 7dbcf84..8f8c58b 100644
--- a/term_reference_tree.module
+++ b/term_reference_tree.module
@@ -139,7 +139,7 @@ function _term_reference_tree_get_children($tid, $vid) {
   $query = db_select('taxonomy_term_data', 't');
   $query->join('taxonomy_term_hierarchy', 'h', 't.tid = h.tid');
   $query->join('taxonomy_vocabulary', 'v', 'v.vid = t.vid');
-  $query->fields('t', array('tid', 'name'));
+  $query->fields('t', array('tid', 'vid', 'name'));
   $query->addField('v', 'machine_name', 'vocabulary_machine_name');
   $query->condition('t.vid', $vid);
   $query->condition('h.parent', $tid);
@@ -218,8 +218,14 @@ function _term_reference_tree_get_options(&$terms, &$allowed, $filter) {
   if (is_array($terms) && count($terms) > 0) {
     foreach ($terms as $term) {
       if (!$filter || (is_array($allowed) && $allowed[$term->tid])) {
-        $options[$term->tid] = entity_label('taxonomy_term', $term);
-        $options += _term_reference_tree_get_options($term->children, $allowed, $filter);
+        // do not use entity_label() for non-term elements
+        if (empty($term->tid)) {
+          $options[''] = $term->name;
+        }
+        else {
+          $options[$term->tid] = entity_label('taxonomy_term', $term);
+          $options += _term_reference_tree_get_options($term->children, $allowed, $filter);
+        }
       }
     }
   }
diff --git a/term_reference_tree.widget.inc b/term_reference_tree.widget.inc
index 1685a43..0aa3e72 100644
--- a/term_reference_tree.widget.inc
+++ b/term_reference_tree.widget.inc
@@ -286,9 +286,10 @@ function term_reference_tree_process_checkbox_tree($element, $form_state) {
       if ($element['#max_choices'] == 1 && !$required) {
         array_unshift($element['#options_tree'], (object) array(
           'tid' => '',
-          'name' => 'N/A',
+          'name' => t('N/A'),
           'depth' => 0,
           'vocabulary_machine_name' => $element['#vocabulary']->machine_name,
+          'children' => array(),
         ));
       }
       $element['#options'] = _term_reference_tree_get_options($element['#options_tree'], $allowed, $element['#filter_view']);