diff --git a/src/Traits/ModelTree.php b/src/Traits/ModelTree.php
index c45f0c9..128237e 100755
--- a/src/Traits/ModelTree.php
+++ b/src/Traits/ModelTree.php
@@ -304,7 +304,7 @@ trait ModelTree
      * @param  string  $space
      * @return array
      */
-    protected function buildSelectOptions(array $nodes = [], $parentId = 0, $prefix = '', $space = ' ')
+    public function buildSelectOptions(array $nodes = [], $parentId = 0, $prefix = '', $space = ' ')
     {
         $d = '├─';
         $prefix = $prefix ?: $d.$space;