diff --git a/Models/Project.php b/Models/Project.php
index 6ff86f3..1742156 100644
--- a/Models/Project.php
+++ b/Models/Project.php
@@ -14,6 +14,8 @@ declare(strict_types=1);
 
 namespace Modules\ProjectManagement\Models;
 
+use Modules\Admin\Models\Account;
+use Modules\Admin\Models\NullAccount;
 use Modules\Calendar\Models\Calendar;
 use Modules\Media\Models\Media;
 use Modules\Media\Models\NullMedia;
@@ -161,10 +163,10 @@ class Project
     /**
      * Created by.
      *
-     * @var int|\Modules\Admin\Models\Account
+     * @var Account
      * @since 1.0.0
      */
-    private $createdBy = 0;
+    private Account $createdBy;
 
     /**
      * Tasks.
@@ -189,6 +191,7 @@ class Project
 
         $this->endEstimated = clone $this->end;
         $this->createdAt    = new \DateTime('now');
+        $this->createdBy    = new NullAccount();
 
         $this->calendar = new Calendar();
 
@@ -704,11 +707,11 @@ class Project
     /**
      * Get created by
      *
-     * @return int|\Modules\Admin\Models\Account
+     * @return Account
      *
      * @since 1.0.0
      */
-    public function getCreatedBy()
+    public function getCreatedBy() : Account
     {
         return $this->createdBy;
     }
@@ -716,11 +719,11 @@ class Project
     /**
      * Set created by
      *
-     * @param int $createdBy Creator
+     * @param Account $createdBy Creator
      *
      * @since 1.0.0
      */
-    public function setCreatedBy(int $createdBy) : void
+    public function setCreatedBy(Account $createdBy) : void
     {
         $this->createdBy = $createdBy;
     }
diff --git a/Models/ProjectMapper.php b/Models/ProjectMapper.php
index da4d4ec..3df4a1f 100644
--- a/Models/ProjectMapper.php
+++ b/Models/ProjectMapper.php
@@ -14,6 +14,7 @@ declare(strict_types=1);
 
 namespace Modules\ProjectManagement\Models;
 
+use Modules\Admin\Models\AccountMapper;
 use Modules\Calendar\Models\CalendarMapper;
 use Modules\Media\Models\MediaMapper;
 use Modules\Tasks\Models\TaskMapper;
@@ -50,7 +51,7 @@ final class ProjectMapper extends DataMapperAbstract
         'projectmanagement_project_endestimated'    => ['name' => 'projectmanagement_project_endestimated',    'type' => 'DateTime',     'internal' => 'endEstimated'],
         'projectmanagement_project_progress'        => ['name' => 'projectmanagement_project_progress',        'type' => 'int',          'internal' => 'progress'],
         'projectmanagement_project_progress_type'   => ['name' => 'projectmanagement_project_progress_type',   'type' => 'int',          'internal' => 'progressType'],
-        'projectmanagement_project_created_by'      => ['name' => 'projectmanagement_project_created_by',      'type' => 'int',          'internal' => 'createdBy'],
+        'projectmanagement_project_created_by'      => ['name' => 'projectmanagement_project_created_by',      'type' => 'int',          'internal' => 'createdBy', 'readonly' => true],
         'projectmanagement_project_created_at'      => ['name' => 'projectmanagement_project_created_at',      'type' => 'DateTime',     'internal' => 'createdAt', 'readonly' => true],
     ];
 
@@ -88,6 +89,19 @@ final class ProjectMapper extends DataMapperAbstract
         ],
     ];
 
+    /**
+     * Belongs to.
+     *
+     * @var array<string, array{mapper:string, self:string}>
+     * @since 1.0.0
+     */
+    protected static array $belongsTo = [
+        'createdBy' => [
+            'mapper' => AccountMapper::class,
+            'self'   => 'projectmanagement_project_created_by',
+        ],
+    ];
+
     /**
      * Primary table.
      *