diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 716fef3..3e35103 100755
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -137,8 +137,8 @@ final class ApiController extends Controller
         $unit->descriptionRaw = $request->getDataString('description') ?? $unit->descriptionRaw;
         $unit->description    = Markdown::parse($request->getDataString('description') ?? $unit->descriptionRaw);
 
-        $parent       = (int) $request->getData('parent');
-        $unit->parent = empty($parent) ? $unit->parent : new NullUnit($parent);
+        $parent       = $request->getDataInt('parent') ?? 0;
+        $unit->parent = $parent === 0 ? $unit->parent : new NullUnit($parent);
         $unit->setStatus($request->getDataInt('status') ?? $unit->getStatus());
 
         return $unit;
diff --git a/Models/Department.php b/Models/Department.php
index 73b14e8..e5c6eac 100755
--- a/Models/Department.php
+++ b/Models/Department.php
@@ -43,10 +43,10 @@ class Department implements \JsonSerializable
     /**
      * Parent
      *
-     * @var self
+     * @var null|self
      * @since 1.0.0
      */
-    public self $parent;
+    public ?self $parent = null;
 
     /**
      * Status
@@ -90,7 +90,6 @@ class Department implements \JsonSerializable
     public function __construct(string $name = '')
     {
         $this->name   = $name;
-        $this->parent = new NullDepartment();
         $this->unit   = new NullUnit();
     }
 
diff --git a/Models/Position.php b/Models/Position.php
index bc3e2ad..cee22c5 100755
--- a/Models/Position.php
+++ b/Models/Position.php
@@ -43,10 +43,10 @@ class Position implements \JsonSerializable
     /**
      * Parent
      *
-     * @var Position
+     * @var null|Position
      * @since 1.0.0
      */
-    public self $parent;
+    public ?self $parent = null;
 
     /**
      * Department
@@ -87,7 +87,6 @@ class Position implements \JsonSerializable
      */
     public function __construct()
     {
-        $this->parent     = new NullPosition();
         $this->department = new NullDepartment();
     }
 
@@ -129,7 +128,7 @@ class Position implements \JsonSerializable
             'description'    => $this->description,
             'descriptionRaw' => $this->descriptionRaw,
             'department'     => $this->department ?? new NullDepartment(),
-            'parent'         => $this->parent ?? null,
+            'parent'         => $this->parent,
         ];
     }
 
diff --git a/Models/Unit.php b/Models/Unit.php
index b08b3a7..96171f8 100755
--- a/Models/Unit.php
+++ b/Models/Unit.php
@@ -56,10 +56,10 @@ class Unit implements \JsonSerializable
     /**
      * Parent
      *
-     * @var Unit
+     * @var null|Unit
      * @since 1.0.0
      */
-    public self $parent;
+    public ?self $parent;
 
     /**
      * Description.
@@ -97,7 +97,6 @@ class Unit implements \JsonSerializable
     public function __construct()
     {
         $this->image       = new NullMedia();
-        $this->parent      = new NullUnit();
         $this->mainAddress = new NullAddress();
     }
 
@@ -150,7 +149,7 @@ class Unit implements \JsonSerializable
             'status'         => $this->status,
             'description'    => $this->description,
             'descriptionRaw' => $this->descriptionRaw,
-            'parent'         => $this->parent ?? null,
+            'parent'         => $this->parent,
             'image'          => $this->image,
         ];
     }
diff --git a/tests/Controller/ApiControllerTest.php b/tests/Controller/ApiControllerTest.php
index 5843b67..3b921bc 100755
--- a/tests/Controller/ApiControllerTest.php
+++ b/tests/Controller/ApiControllerTest.php
@@ -82,7 +82,7 @@ final class ApiControllerTest extends \PHPUnit\Framework\TestCase
         $this->app->accountManager->add($account);
         $this->app->router = new WebRouter();
 
-        $this->module = $this->app->moduleManager->get('Organization');
+        $this->module = $this->app->moduleManager->get('Organization', 'Api');
 
         TestUtils::setMember($this->module, 'app', $this->app);
     }