diff --git a/Sms77Transport.php b/Sms77Transport.php
index 6761ec1..372ec2a 100644
--- a/Sms77Transport.php
+++ b/Sms77Transport.php
@@ -31,7 +31,7 @@ final class Sms77Transport extends AbstractTransport
     private string $apiKey;
     private ?string $from;
 
-    public function __construct(#[\SensitiveParameter] string $apiKey, string $from = null, HttpClientInterface $client = null, EventDispatcherInterface $dispatcher = null)
+    public function __construct(#[\SensitiveParameter] string $apiKey, ?string $from = null, ?HttpClientInterface $client = null, ?EventDispatcherInterface $dispatcher = null)
     {
         $this->apiKey = $apiKey;
         $this->from = $from;
diff --git a/Tests/Sms77TransportTest.php b/Tests/Sms77TransportTest.php
index 3c46483..0a1ad1f 100644
--- a/Tests/Sms77TransportTest.php
+++ b/Tests/Sms77TransportTest.php
@@ -21,7 +21,7 @@
 
 final class Sms77TransportTest extends TransportTestCase
 {
-    public static function createTransport(HttpClientInterface $client = null, string $from = null): Sms77Transport
+    public static function createTransport(?HttpClientInterface $client = null, ?string $from = null): Sms77Transport
     {
         return new Sms77Transport('apiKey', $from, $client ?? new MockHttpClient());
     }