diff --git a/lib/Api/AbstractV1Api.php b/lib/Api/AbstractV1Api.php
index 12d115a..0189a29 100644
--- a/lib/Api/AbstractV1Api.php
+++ b/lib/Api/AbstractV1Api.php
@@ -41,11 +41,11 @@ abstract class AbstractV1Api
     protected ?LoggerInterface $logger;
 
     public function __construct(
-        ClientConfigInterface $clientConfig = null,
-        ClientInterface $client = null,
-        SerializerInterface $serializer = null,
-        RequestFactory $requestFactory = null,
-        LoggerInterface $logger = null
+        ?ClientConfigInterface $clientConfig = null,
+        ?ClientInterface $client = null,
+        ?SerializerInterface $serializer = null,
+        ?RequestFactory $requestFactory = null,
+        ?LoggerInterface $logger = null
     ) {
         $this->clientConfig = $clientConfig ?: new ClientConfig();
         $this->client = $client ?: new Client();
@@ -104,7 +104,7 @@ protected function sendRequestAndHandleResponse(
         return $response;
     }
 
-    protected function createHttpPostRequest(string $path, array $headers = [], string $httpBody = null): Request
+    protected function createHttpPostRequest(string $path, array $headers = [], ?string $httpBody = null): Request
     {
         $uri = rtrim($this->clientConfig->getServiceUrl(), '/') . $path;
         if ($this->logger !== null) {
diff --git a/src/Logger/MetricsLogHandler.php b/src/Logger/MetricsLogHandler.php
index faf659c..4c4ae78 100644
--- a/src/Logger/MetricsLogHandler.php
+++ b/src/Logger/MetricsLogHandler.php
@@ -11,7 +11,7 @@ class MetricsLogHandler extends BaseLogger
 {
     private const LOG_FILENAME = '/var/log/rar_prometheus_metric.log';
 
-    public function __construct(DriverInterface $filesystem, string $filePath = null)
+    public function __construct(DriverInterface $filesystem, ?string $filePath = null)
     {
         parent::__construct($filesystem, $filePath, self::LOG_FILENAME);
     }