diff --git a/hierarchical_select.module b/hierarchical_select.module
index d782cd3..21d80cb 100644
--- a/hierarchical_select.module
+++ b/hierarchical_select.module
@@ -1394,7 +1394,7 @@ function _hs_process_render_flat_select($hierarchy, $dropbox, $config) {
  * @return
  *   A single item id or a flat array of item ids.
  */
-function _hierarchical_select_process_calculate_return_value($hierarchy, $dropbox = FALSE, $module, $params, $save_lineage) {
+function _hierarchical_select_process_calculate_return_value($hierarchy, $dropbox, $module, $params, $save_lineage) {
   if (!$dropbox) {
     $return_value = _hierarchical_select_hierarchy_validate($hierarchy->lineage, $module, $params);
     // If the save_lineage setting is disabled, keep only the deepest item.