diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 45a2072..b033cad 100755
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -79,8 +79,8 @@ final class ApiController extends Controller
         $doc = $this->createWikiDocFromRequest($request, $response, $data);
         $this->createModel($request->header->account, $doc, WikiDocMapper::class, 'doc', $request->getOrigin());
 
-        if (!empty($request->getFiles() ?? [])
-            || !empty($request->getDataJson('media') ?? [])
+        if (!empty($request->getFiles())
+            || !empty($request->getDataJson('media'))
         ) {
             $this->createWikiMedia($doc, $request);
         }
@@ -108,7 +108,7 @@ final class ApiController extends Controller
         $path    = $this->createWikiDir($doc);
         $account = AccountMapper::get()->where('id', $request->header->account)->execute();
 
-        if (!empty($uploadedFiles = $request->getFiles() ?? [])) {
+        if (!empty($uploadedFiles = $request->getFiles())) {
             $uploaded = $this->app->moduleManager->get('Media')->uploadFiles(
                 [],
                 [],
@@ -146,7 +146,7 @@ final class ApiController extends Controller
             }
         }
 
-        if (!empty($mediaFiles = $request->getDataJson('media') ?? [])) {
+        if (!empty($mediaFiles = $request->getDataJson('media'))) {
             $collection = null;
 
             foreach ($mediaFiles as $media) {
diff --git a/Models/WikiCategoryMapper.php b/Models/WikiCategoryMapper.php
index 6a9f198..0cc1779 100755
--- a/Models/WikiCategoryMapper.php
+++ b/Models/WikiCategoryMapper.php
@@ -59,7 +59,7 @@ final class WikiCategoryMapper extends DataMapperFactory
     /**
      * Has owns one relation.
      *
-     * @var array<string, array<string, null|string>>
+     * @var array<string, array{mapper:string, external:string}>
      * @since 1.0.0
      */
     public const BELONGS_TO = [
diff --git a/Models/WikiDocMapper.php b/Models/WikiDocMapper.php
index 1754c89..3113462 100755
--- a/Models/WikiDocMapper.php
+++ b/Models/WikiDocMapper.php
@@ -74,7 +74,7 @@ final class WikiDocMapper extends DataMapperFactory
     /**
      * Has owns one relation.
      *
-     * @var array<string, array<string, null|string>>
+     * @var array<string, array{mapper:string, external:string}>
      * @since 1.0.0
      */
     public const BELONGS_TO = [
diff --git a/composer.json b/composer.json
index b90cb5e..10044a1 100755
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         "friendsofphp/php-cs-fixer": ">=3.2",
         "squizlabs/php_codesniffer": ">=3.6",
         "phpmd/phpmd": ">=2.9",
-        "phpstan/phpstan": ">=0.12.58",
+        "phpstan/phpstan": ">=1.5.4",
         "phan/phan": ">=3.2.6"
     },
     "minimum-stability": "dev",