diff --git a/Admin/Installer.php b/Admin/Installer.php
index 496260a..eb824d2 100644
--- a/Admin/Installer.php
+++ b/Admin/Installer.php
@@ -14,6 +14,7 @@ declare(strict_types=1);
 
 namespace Modules\Media\Admin;
 
+use Modules\Admin\Models\NullAccount;
 use Modules\Media\Models\Collection;
 
 use Modules\Media\Models\CollectionMapper;
@@ -85,7 +86,7 @@ final class Installer extends InstallerAbstract
         $collection->setName((string) $data['name'] ?? '');
         $collection->setVirtualPath((string) $data['virtualPath'] ?? '/');
         $collection->setPath((string) $data['virtualPath'] ?? '/');
-        $collection->setCreatedBy((int) $data['user'] ?? 1);
+        $collection->setCreatedBy(new NullAccount((int) $data['user'] ?? 1));
 
         CollectionMapper::create($collection);
     }
diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 2da1891..2d5aa38 100644
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -15,6 +15,7 @@ declare(strict_types=1);
 namespace Modules\Media\Controller;
 
 use Modules\Admin\Models\AccountPermission;
+use Modules\Admin\Models\NullAccount;
 use Modules\Media\Models\Collection;
 use Modules\Media\Models\CollectionMapper;
 use Modules\Media\Models\Media;
@@ -23,8 +24,8 @@ use Modules\Media\Models\NullCollection;
 use Modules\Media\Models\PathSettings;
 use Modules\Media\Models\PermissionState;
 use Modules\Media\Models\UploadFile;
-use Modules\Media\Models\UploadStatus;
 
+use Modules\Media\Models\UploadStatus;
 use phpOMS\Account\PermissionType;
 use phpOMS\Message\NotificationLevel;
 use phpOMS\Message\RequestAbstract;
@@ -240,7 +241,7 @@ final class ApiController extends Controller
             $media->setPath(self::normalizeDbPath($status['path']) . '/' . $status['filename']);
             $media->setName($status['name']);
             $media->setSize($status['size']);
-            $media->setCreatedBy($account);
+            $media->setCreatedBy(new NullAccount($account));
             $media->setExtension($status['extension']);
             $media->setVirtualPath($virtualPath);
 
diff --git a/Models/Collection.php b/Models/Collection.php
index ed62aab..6550b78 100644
--- a/Models/Collection.php
+++ b/Models/Collection.php
@@ -27,10 +27,10 @@ class Collection extends Media implements \Iterator
     /**
      * Resource id.
      *
-     * @var array<int, int|Media>
+     * @var Media[]
      * @since 1.0.0
      */
-    private $sources = [];
+    private array $sources = [];
 
     /**
      * Extension name.
@@ -65,13 +65,13 @@ class Collection extends Media implements \Iterator
     /**
      * Set sources.
      *
-     * @param int|Media $source Source
+     * @param Media $source Source
      *
      * @return void
      *
      * @since 1.0.0
      */
-    public function addSource($source) : void
+    public function addSource(Media $source) : void
     {
         $this->sources[] = $source;
     }
@@ -79,7 +79,7 @@ class Collection extends Media implements \Iterator
     /**
      * Get sources.
      *
-     * @return array
+     * @return Media[]
      *
      * @since 1.0.0
      */
diff --git a/Models/Media.php b/Models/Media.php
index 2d2083d..69127f2 100644
--- a/Models/Media.php
+++ b/Models/Media.php
@@ -14,6 +14,9 @@ declare(strict_types=1);
 
 namespace Modules\Media\Models;
 
+use Modules\Admin\Models\Account;
+use Modules\Admin\Models\NullAccount;
+
 /**
  * Media class.
  *
@@ -59,10 +62,10 @@ class Media implements \JsonSerializable
     /**
      * Author.
      *
-     * @var int
+     * @var Account
      * @since 1.0.0
      */
-    protected $createdBy = 0;
+    protected Account $createdBy;
 
     /**
      * Uploaded.
@@ -151,6 +154,7 @@ class Media implements \JsonSerializable
      */
     public function __construct()
     {
+        $this->createdBy = new NullAccount();
         $this->createdAt = new \DateTime();
     }
 
@@ -297,11 +301,11 @@ class Media implements \JsonSerializable
     }
 
     /**
-     * @return int|\phpOMS\Account\Account
+     * @return Account
      *
      * @since 1.0.0
      */
-    public function getCreatedBy()
+    public function getCreatedBy() : Account
     {
         return $this->createdBy;
     }
@@ -313,7 +317,7 @@ class Media implements \JsonSerializable
      */
     public function getCreatedAt() : \DateTime
     {
-        return $this->createdAt ?? new \DateTime('now');
+        return $this->createdAt;
     }
 
     /**
@@ -397,13 +401,13 @@ class Media implements \JsonSerializable
     }
 
     /**
-     * @param mixed $createdBy Creator
+     * @param Account $createdBy Creator
      *
      * @return void
      *
      * @since 1.0.0
      */
-    public function setCreatedBy($createdBy) : void
+    public function setCreatedBy(Account $createdBy) : void
     {
         $this->createdBy = $createdBy;
     }
diff --git a/Models/MediaMapper.php b/Models/MediaMapper.php
index 7642676..0ed9842 100644
--- a/Models/MediaMapper.php
+++ b/Models/MediaMapper.php
@@ -47,7 +47,7 @@ class MediaMapper extends DataMapperAbstract
         'media_password'        => ['name' => 'media_password',        'type' => 'string',   'internal' => 'password'],
         'media_extension'       => ['name' => 'media_extension',       'type' => 'string',   'internal' => 'extension'],
         'media_size'            => ['name' => 'media_size',            'type' => 'int',      'internal' => 'size'],
-        'media_created_by'      => ['name' => 'media_created_by',      'type' => 'int',      'internal' => 'createdBy'],
+        'media_created_by'      => ['name' => 'media_created_by',      'type' => 'int',      'internal' => 'createdBy', 'readonly' => true],
         'media_created_at'      => ['name' => 'media_created_at',      'type' => 'DateTime', 'internal' => 'createdAt', 'readonly' => true],
     ];
 
diff --git a/Models/NullCollection.php b/Models/NullCollection.php
index 1d22b9c..31a1b12 100644
--- a/Models/NullCollection.php
+++ b/Models/NullCollection.php
@@ -24,4 +24,15 @@ namespace Modules\Media\Models;
  */
 final class NullCollection extends Collection
 {
+    /**
+     * Constructor
+     *
+     * @param int $id Model id
+     *
+     * @since 1.0.0
+     */
+    public function __construct(int $id = 0)
+    {
+        $this->id = $id;
+    }
 }
diff --git a/Models/NullMedia.php b/Models/NullMedia.php
index 80c6101..2ab29e5 100644
--- a/Models/NullMedia.php
+++ b/Models/NullMedia.php
@@ -24,4 +24,15 @@ namespace Modules\Media\Models;
  */
 final class NullMedia extends Media
 {
+    /**
+     * Constructor
+     *
+     * @param int $id Model id
+     *
+     * @since 1.0.0
+     */
+    public function __construct(int $id = 0)
+    {
+        $this->id = $id;
+    }
 }