diff --git a/application/Espo/Core/Utils/Database/Orm/Fields/LinkParent.php b/application/Espo/Core/Utils/Database/Orm/Fields/LinkParent.php
index 040f2563d9..10b1c2a519 100644
--- a/application/Espo/Core/Utils/Database/Orm/Fields/LinkParent.php
+++ b/application/Espo/Core/Utils/Database/Orm/Fields/LinkParent.php
@@ -16,7 +16,8 @@ class LinkParent extends \Espo\Core\Utils\Database\Orm\Base
 					),
 					$field['name'].'Type' => array(
 						'type' => 'foreignType',
-						'index' => $field['name'],
+						'notnull' => false,
+						'index' => $field['name'], 						 
 					),
 					$field['name'].'Name' => array(
 						'type' => 'varchar',