diff --git a/term_reference_tree.widget.inc b/term_reference_tree.widget.inc
index d1438313..bef3cbdc 100644
--- a/term_reference_tree.widget.inc
+++ b/term_reference_tree.widget.inc
@@ -677,6 +677,7 @@ function _term_reference_tree_widget_validate(&$element, &$form_state) {
 	  return $element;
 	}else{
 		# if the field was not in the form
+    $values = array();
 		foreach ($element['#default_value'] as $tid) {
       $values[] = (array) taxonomy_term_load($tid);
 		}