diff --git a/Tests/LokaliseProviderTest.php b/Tests/LokaliseProviderTest.php
index 617a43a..bb03df7 100644
--- a/Tests/LokaliseProviderTest.php
+++ b/Tests/LokaliseProviderTest.php
@@ -31,7 +31,7 @@
 
 class LokaliseProviderTest extends ProviderTestCase
 {
-    public static function createProvider(HttpClientInterface $client, LoaderInterface $loader, LoggerInterface $logger, string $defaultLocale, string $endpoint, TranslatorBagInterface $translatorBag = null): ProviderInterface
+    public static function createProvider(HttpClientInterface $client, LoaderInterface $loader, LoggerInterface $logger, string $defaultLocale, string $endpoint, ?TranslatorBagInterface $translatorBag = null): ProviderInterface
     {
         return new LokaliseProvider($client, $loader, $logger, $defaultLocale, $endpoint);
     }