diff --git a/taxonomy_manager.admin.inc b/taxonomy_manager.admin.inc
index e86a39b..50c934d 100644
--- a/taxonomy_manager.admin.inc
+++ b/taxonomy_manager.admin.inc
@@ -184,7 +184,7 @@ function taxonomy_manager_form($form, &$form_state, $voc, $tid = 0, $filter = NU
     $tids_to_expand = $form_state['values']['searched_terms'];
   }
   else {
-    $tids_to_expand = $tid;
+    $tids_to_expand = $tid ? [$tid] : [];
   }
 
   $form['taxonomy']['manager']['tree'] = [