diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index a37a7c8..f460e04 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -32,11 +32,7 @@ jobs:
     name: PHPStan
     steps:
     - uses: actions/checkout@v5
-    - name: Use PHP 8.3
-      uses: shivammathur/setup-php@v2
-      with:
-        php-version: 8.3
-        extensions: curl
+    - uses: shivammathur/setup-php@v2
     - name: Install dependencies
       run: composer install --no-progress
     - name: Run PHPStan
diff --git a/composer.json b/composer.json
old mode 100755
new mode 100644
index a0cc6f0..be43281
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
     },
     "require-dev": {
         "geocoder-php/nominatim-provider": "^5.3",
-        "phpstan/phpstan": "^1.10"
+        "phpstan/phpstan": "^1.10 || ^2.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/BaseTestCase.php b/src/BaseTestCase.php
index 9e5d1e0..a74dc89 100644
--- a/src/BaseTestCase.php
+++ b/src/BaseTestCase.php
@@ -31,7 +31,7 @@ abstract protected function getCacheDir();
     /**
      * Get a real HTTP client. If a cache dir is set to a path it will use cached responses.
      */
-    protected function getHttpClient(string $apiKey = null): ClientInterface
+    protected function getHttpClient(?string $apiKey = null): ClientInterface
     {
         if (null !== $cacheDir = $this->getCacheDir()) {
             return new CachedResponseClient(new HttplugClient(), $cacheDir, $apiKey);
@@ -43,7 +43,7 @@ protected function getHttpClient(string $apiKey = null): ClientInterface
     /**
      * Get a mocked HTTP client that never do calls over the internet. Use this is you want to control the response data.
      */
-    protected function getMockedHttpClient(string $body = null, int $statusCode = 200): ClientInterface
+    protected function getMockedHttpClient(?string $body = null, int $statusCode = 200): ClientInterface
     {
         $client = new MockedHttpClient();
         $client->addResponse(new Response($statusCode, [], $body));
diff --git a/src/ProviderIntegrationTest.php b/src/ProviderIntegrationTest.php
index 94ca1c0..ef85d2a 100644
--- a/src/ProviderIntegrationTest.php
+++ b/src/ProviderIntegrationTest.php
@@ -213,7 +213,7 @@ public function testGeocodeIpv6(): void
      * @param ResponseInterface|null    $response
      * @param string                    $message
      */
-    public function testExceptions($query, string $exceptionClass, ResponseInterface $response = null, string $message = ''): void
+    public function testExceptions($query, string $exceptionClass, ?ResponseInterface $response = null, string $message = ''): void
     {
         if (isset($this->skippedTests[__FUNCTION__])) {
             $this->markTestSkipped($this->skippedTests[__FUNCTION__]);
@@ -311,7 +311,6 @@ private function assertWellFormattedResult(Collection $result): void
                 'Location::getAdminLevels MUST always return a AdminLevelCollection'
             );
             $arrayData = $location->toArray();
-            $this->assertTrue(is_array($arrayData), 'Location::toArray MUST return an array.');
             $this->assertNotEmpty($arrayData, 'Location::toArray cannot be empty.');
 
             // Verify coordinates