diff --git a/modules/backend/behaviors/ReorderController.php b/modules/backend/behaviors/ReorderController.php
index <HASH>..<HASH> 100644
--- a/modules/backend/behaviors/ReorderController.php
+++ b/modules/backend/behaviors/ReorderController.php
@@ -214,7 +214,10 @@ class ReorderController extends ControllerBehavior
         $model = $this->controller->reorderGetModel();
         $modelTraits = class_uses($model);
 
-        if (isset($modelTraits[\October\Rain\Database\Traits\Sortable::class])) {
+        if (
+            isset($modelTraits[\October\Rain\Database\Traits\Sortable::class]) ||
+            $model->isClassExtendedWith(\October\Rain\Database\Behaviors\Sortable::class)
+        ) {
             $this->sortMode = 'simple';
         }
         elseif (isset($modelTraits[\October\Rain\Database\Traits\NestedTree::class])) {
@@ -222,7 +225,7 @@ class ReorderController extends ControllerBehavior
             $this->showTree = true;
         }
         else {
-            throw new ApplicationException('The model must implement the NestedTree or Sortable traits.');
+            throw new ApplicationException('The model must implement the Sortable trait/behavior or the NestedTree trait.');
         }
 
         return $model;
Add Sortable Behavior to ReorderController validateModel (#<I>)

Checks for the newly added Sortable Behavior as well as the existing Sortable Trait. See <URL>