--- a/modules/hs_taxonomy.module
+++ b/modules/hs_taxonomy.module
@@ -181,6 +181,9 @@ function hs_taxonomy_form_taxonomy_form_term_alter(&$form, &$form_state) {
 
   // Use Hierarchical Select for selecting the parent term(s).
   $parent = isset($form['#term']['tid']) ? array_keys(taxonomy_get_parents($form['#term']['tid'])) : array(0);
+  if (empty($parent)) {
+    $parent = array(0);
+  }
   $form['relations']['parent'] = array(
     '#type'          => 'hierarchical_select',
     '#title'         => t('Parents'),