diff --git a/.github/workflows/php-tests.yml b/.github/workflows/php-tests.yml
index 8c35057..52d65a9 100644
--- a/.github/workflows/php-tests.yml
+++ b/.github/workflows/php-tests.yml
@@ -59,7 +59,9 @@ jobs:
       - name: "Install PHP"
         uses: "shivammathur/setup-php@v2"
         with:
-          php-version: "latest"
+          # Use PHP 8.3 until psalm resolves issues with 8.4
+          # https://github.com/vimeo/psalm/issues/11107
+          php-version: "8.3"
           coverage: "none"
 
       - name: "Install dependencies (Composer)"
diff --git a/src/Config/ConfigInterface.php b/src/Config/ConfigInterface.php
index 021def6..5ac2a99 100644
--- a/src/Config/ConfigInterface.php
+++ b/src/Config/ConfigInterface.php
@@ -8,7 +8,7 @@ public function getProduction(): bool;
     public function getSameSiteStrict(): ?bool;
     /**  @return array<string, int|string>|null */
     public function getError(): ?array;
-    /**  @return array<string, string>|null */
+    /**  @return array<string>|null */
     public function getScope(): ?array;
     /**  @return array<string>|null */
     public function getProviderHint(): ?array;
diff --git a/src/Exception/CallbackException.php b/src/Exception/CallbackException.php
index 9142f3f..8d2efa7 100644
--- a/src/Exception/CallbackException.php
+++ b/src/Exception/CallbackException.php
@@ -7,11 +7,11 @@
 
 class CallbackException extends Exception
 {
-    /** @var array<string, string> */
+    /** @var array<string, mixed> */
     private array $errorDetails;
 
     /**
-     * @param array<string, string> $errorDetails
+     * @param array<string, mixed> $errorDetails
      * @param string $message
      * @param int $code
      * @param Throwable|null $previous
@@ -27,7 +27,7 @@ public function __construct(
     }
 
     /**
-     * @return array<string, string>
+     * @return array<string, mixed>
      */
     public function getErrorDetails(): array
     {
diff --git a/src/Handler/Callback.php b/src/Handler/Callback.php
index 6fc2d15..da8f29e 100644
--- a/src/Handler/Callback.php
+++ b/src/Handler/Callback.php
@@ -262,7 +262,7 @@ public function handleCallback(): string
      * Uses the target URI from error details or a fallback error route. Updates the query
      * string with error information. Throws an exception if no error URI is available.
      *
-     * @param array<string, string> $error Error details including 'target_uri', 'error', and 'error_description'.
+     * @param array<string, mixed> $error Error details including 'target_uri', 'error', and 'error_description'.
      * @param string $errorMessage A message describing the error.
      * @param Throwable|null $previous Previous exception for chaining (optional).
      *
@@ -272,6 +272,7 @@ public function handleCallback(): string
      */
     private function sendErrorPage(array $error, string $errorMessage, ?Throwable $previous = null): string
     {
+        /** @var string $error_uri */
         $error_uri = $error['target_uri'] ?? $this->config->getRoutes()['error'] ?? null;
         if ($error_uri) {
             list($pathString, $queryString) = array_pad(explode('?', (string) $error_uri, 2), 2, '');
diff --git a/src/Handler/Login.php b/src/Handler/Login.php
index bc1557b..196b379 100644
--- a/src/Handler/Login.php
+++ b/src/Handler/Login.php
@@ -82,13 +82,16 @@ public function generateLoginUrl(): string
         }
 
         $redirectURI = $this->config->getRedirectURI();
+        /** @var string $host */
         $host = $this->helloRequest->fetchHeader('Host');
 
         if (empty($redirectURI)) {
             if (isset($this->redirectURIs[$host])) {
                 $redirectURI = $this->redirectURIs[$host];
             } elseif (!empty($params['redirect_uri'])) {
-                $this->redirectURIs[$host] = $redirectURI = $params['redirect_uri'];
+                /** @var string $redirectURI */
+                $redirectURI = $params['redirect_uri'];
+                $this->redirectURIs[$host] = $redirectURI;
                 error_log("Hello: RedirectURI for $host => $redirectURI");
             } else {
                 error_log('Hello: Discovering API RedirectURI route ...');
@@ -97,9 +100,11 @@ public function generateLoginUrl(): string
             }
         }
 
+        /** @var string $providerHintString */
         $providerHintString = $params['provider_hint'];
         $providerHint = $providerHintString ? array_map('trim', explode(' ', $providerHintString)) : null;
 
+        /** @var string $scopeString */
         $scopeString = $params['scope'];
         $scope = $scopeString ? array_map('trim', explode(' ', $scopeString)) : null;
 
@@ -120,11 +125,14 @@ public function generateLoginUrl(): string
 
         $authResponse = $this->getAuthHelper()->createAuthRequest($request);
 
+        /** @var string $targetUri */
+        $targetUri = $params['target_uri'];
+
         $this->getOIDCManager()->saveOidc(OIDC::fromArray([
             'nonce' => $authResponse['nonce'],
             'code_verifier' => $authResponse['code_verifier'],
             'redirect_uri' => $redirectURI,
-            'target_uri' => $params['target_uri'],
+            'target_uri' => $targetUri,
         ]));
 
         return $authResponse['url'];
diff --git a/src/Handler/Logout.php b/src/Handler/Logout.php
index e78f7ca..2cc420d 100644
--- a/src/Handler/Logout.php
+++ b/src/Handler/Logout.php
@@ -55,6 +55,7 @@ private function getAuthLib(): AuthLib
      */
     public function generateLogoutUrl(): string
     {
+        /** @var string|null $targetUri */
         $targetUri = $this->helloRequest->fetch('target_uri');
         $this->getAuthLib()->clearAuthCookie();
         if ($this->config->getLogoutSync()) {
diff --git a/src/HelloClient.php b/src/HelloClient.php
index 3da3253..8353f85 100644
--- a/src/HelloClient.php
+++ b/src/HelloClient.php
@@ -141,10 +141,16 @@ private function handleCallback()
             return $this->helloResponse->redirect($this->getCallbackHandler()->handleCallback());
         } catch (CallbackException $e) {
             $errorDetails = $e->getErrorDetails();
+            /** @var string $error */
+            $error =  $errorDetails['error'];
+            /** @var string $errorDescription */
+            $errorDescription =  $errorDetails['error_description'];
+            /** @var string $targetUri */
+            $targetUri =  $errorDetails['target_uri'];
             return $this->helloResponse->render($this->pageRenderer->renderErrorPage(
-                $errorDetails['error'],
-                $errorDetails['error_description'],
-                $errorDetails['target_uri']
+                $error,
+                $errorDescription,
+                $targetUri
             ));
         } catch (SameSiteCallbackException $e) {
             return $this->helloResponse->render($this->pageRenderer->renderSameSitePage());
@@ -153,7 +159,7 @@ private function handleCallback()
 
     /**
      * @return mixed|string|void|null
-     * @throws CryptoFailedException | InvalidSecretException
+     * @throws CryptoFailedException | InvalidSecretException | Exception
      */
     public function route()
     {
diff --git a/src/HelloRequest/HelloRequest.php b/src/HelloRequest/HelloRequest.php
index 2c68f2d..875efeb 100644
--- a/src/HelloRequest/HelloRequest.php
+++ b/src/HelloRequest/HelloRequest.php
@@ -10,10 +10,10 @@ class HelloRequest implements HelloRequestInterface
      * Fetch a parameter by key from either GET or POST data.
      *
      * @param string $key The key of the parameter to fetch.
-     * @param string|null $default Default value if the key is not found.
-     * @return string|null The value of the parameter or default.
+     * @param mixed $default Default value if the key is not found.
+     * @return mixed The value of the parameter or default.
      */
-    public function fetch(string $key, ?string $default = null): ?string
+    public function fetch(string $key, $default = null)
     {
         // First check GET, then POST if not found.
         return $_GET[$key] ?? $_POST[$key] ?? $default;
@@ -23,7 +23,7 @@ public function fetch(string $key, ?string $default = null): ?string
      * Fetch multiple parameters by keys from either GET or POST data.
      *
      * @param array<string> $keys The keys of the parameters to fetch.
-     * @return array<string, string|null> An associative array of parameters.
+     * @return array<string, mixed> An associative array of parameters.
      */
     public function fetchMultiple(array $keys): array
     {
@@ -38,10 +38,10 @@ public function fetchMultiple(array $keys): array
      * Fetch a header by key from the request headers.
      *
      * @param string $key The key of the header to fetch.
-     * @param string|null $default Default value if the key is not found.
-     * @return string|null The value of the header or default.
+     * @param mixed|null $default Default value if the key is not found.
+     * @return mixed|null The value of the header or default.
      */
-    public function fetchHeader(string $key, ?string $default = null): ?string
+    public function fetchHeader(string $key, $default = null)
     {
         $headers = $this->getAllHeaders();
         $normalizedKey = strtolower($key);
@@ -56,7 +56,7 @@ public function fetchHeader(string $key, ?string $default = null): ?string
     /**
      * Retrieve all request headers.
      *
-     * @return array<string, string> An associative array of all request headers.
+     * @return array<string, mixed> An associative array of all request headers.
      */
     private function getAllHeaders(): array
     {
diff --git a/src/HelloRequest/HelloRequestInterface.php b/src/HelloRequest/HelloRequestInterface.php
index e26da27..c0c7469 100644
--- a/src/HelloRequest/HelloRequestInterface.php
+++ b/src/HelloRequest/HelloRequestInterface.php
@@ -8,16 +8,16 @@ interface HelloRequestInterface
      * Fetch a parameter by key from either GET or POST data.
      *
      * @param string $key The key of the parameter to fetch.
-     * @param string|null $default Default value if the key is not found.
-     * @return string|null The value of the parameter or default.
+     * @param mixed $default Default value if the key is not found.
+     * @return mixed The value of the parameter or default.
      */
-    public function fetch(string $key, ?string $default = null): ?string;
+    public function fetch(string $key, $default = null);
 
     /**
      * Fetch multiple parameters by keys from either GET or POST data.
      *
      * @param array<string> $keys The keys of the parameters to fetch.
-     * @return array<string, string> An associative array of parameters.
+     * @return array<string, mixed> An associative array of parameters.
      */
     public function fetchMultiple(array $keys): array;
 
@@ -25,10 +25,10 @@ public function fetchMultiple(array $keys): array;
      * Fetch a header by key from the request headers.
      *
      * @param string $key The key of the header to fetch.
-     * @param string|null $default Default value if the key is not found.
-     * @return string|null The value of the header or default.
+     * @param mixed $default Default value if the key is not found.
+     * @return mixed The value of the header or default.
      */
-    public function fetchHeader(string $key, ?string $default = null): ?string;
+    public function fetchHeader(string $key, $default = null);
 
     /**
      * Fetch a cookie value by name.
diff --git a/src/Type/AuthUpdates.php b/src/Type/AuthUpdates.php
index 39cf4ce..c616ef1 100644
--- a/src/Type/AuthUpdates.php
+++ b/src/Type/AuthUpdates.php
@@ -58,9 +58,9 @@ public function offsetExists($offset): bool
         return isset($this->additionalProperties[$offset]);
     }
 
-    public function offsetGet($offset): ?string
+    public function offsetGet($offset): string
     {
-        return is_string($this->additionalProperties[$offset]) ? $this->additionalProperties[$offset] : null;
+        return is_string($this->additionalProperties[$offset]) ? $this->additionalProperties[$offset] : '';
     }
 
     public function offsetSet($offset, $value): void
diff --git a/src/Utils/QueryParamFetcher.php b/src/Utils/QueryParamFetcher.php
index be81398..025ec1d 100644
--- a/src/Utils/QueryParamFetcher.php
+++ b/src/Utils/QueryParamFetcher.php
@@ -5,7 +5,7 @@
 class QueryParamFetcher
 {
     /**
-     * @param array<string, mixed> $keys
+     * @param array<int, string> $keys
      * @return array<string, mixed>
      */
     public static function fetch(array $keys): array
diff --git a/tests/Config/HelloConfigBuilderTest.php b/tests/Config/HelloConfigBuilderTest.php
index 81d31fe..79d58ca 100644
--- a/tests/Config/HelloConfigBuilderTest.php
+++ b/tests/Config/HelloConfigBuilderTest.php
@@ -8,7 +8,7 @@
 
 class HelloConfigBuilderTest extends TestCase
 {
-    public function testHelloConfigBuilderBuildsConfigCorrectly()
+    public function testHelloConfigBuilderBuildsConfigCorrectly(): void
     {
         // Arrange: Create the builder and set values
         $builder = new HelloConfigBuilder();
diff --git a/tests/Handler/AuthTest.php b/tests/Handler/AuthTest.php
index b63229b..38018a7 100644
--- a/tests/Handler/AuthTest.php
+++ b/tests/Handler/AuthTest.php
@@ -38,8 +38,16 @@ public function testCanHandleAuth(): void
         ]);
 
         $result = $this->auth->handleAuth();
+        /** @var string $actual_name */
+        $actual_name = isset($result->toArray()['authCookie']['name'])
+            ? $result->toArray()['authCookie']['name']
+            : '';
+        /** @var string $actual_email */
+        $actual_email = isset($result->toArray()['authCookie']['name'])
+            ? $result->toArray()['authCookie']['email']
+            : '';
         $this->assertTrue($result->toArray()['isLoggedIn']);
-        $this->assertEquals($result->toArray()['authCookie']['name'], 'Dick Hardt');
-        $this->assertEquals($result->toArray()['authCookie']['email'], 'dick.hardt@hello.coop');
+        $this->assertEquals('Dick Hardt', $actual_name);
+        $this->assertEquals('dick.hardt@hello.coop', $actual_email);
     }
 }
diff --git a/tests/Handler/CallbackTest.php b/tests/Handler/CallbackTest.php
index 986eec5..48e56cf 100644
--- a/tests/Handler/CallbackTest.php
+++ b/tests/Handler/CallbackTest.php
@@ -28,7 +28,7 @@ protected function setUp(): void
         $this->tokenFetcherMock->method('fetchToken')->willReturn('valid_token_id');
     }
 
-    public function testHandleCallbackSuccessfulLogin()
+    public function testHandleCallbackSuccessfulLogin(): void
     {
         $_COOKIE['oidcName'] = $this->crypto->encrypt([
             'code_verifier' => 'test_verifier',
@@ -68,7 +68,7 @@ public function testHandleCallbackSuccessfulLogin()
         $this->assertEquals('http://api.example.com?uri=example.com&appName=MyApp&redirectURI=https%3A%2F%2Fexample.com%2Fcallback&targetURI=%2Fdashboard&wildcard_console=true', $result);
     }
 
-    public function testHandleCallbackMissingCode()
+    public function testHandleCallbackMissingCode(): void
     {
         $_COOKIE['oidcName'] = $this->crypto->encrypt([
             'code_verifier' => 'test_verifier',
@@ -86,10 +86,13 @@ public function testHandleCallbackMissingCode()
         ]);
 
 
-        $this->assertEquals('/dashboard?error=invalid_request&error_description=Missing+code+parameter', $this->callback->handleCallback());
+        $this->assertEquals(
+            '/dashboard?error=invalid_request&error_description=Missing+code+parameter',
+            $this->callback->handleCallback()
+        );
     }
 
-    public function testHandleCallbackInvalidTokenAudience()
+    public function testHandleCallbackInvalidTokenAudience(): void
     {
         // Set up mock behaviors
         $_GET = array_merge($_GET, [
diff --git a/tests/Handler/LoginTest.php b/tests/Handler/LoginTest.php
index aa5f156..189a79d 100644
--- a/tests/Handler/LoginTest.php
+++ b/tests/Handler/LoginTest.php
@@ -36,7 +36,7 @@ protected function setUp(): void
         );
     }
 
-    public function testGenerateLoginUrlSuccess()
+    public function testGenerateLoginUrlSuccess(): void
     {
         // Setup mocks
         $_GET = [
@@ -67,15 +67,16 @@ public function testGenerateLoginUrlSuccess()
         );
 
         $query = parse_url($url, PHP_URL_QUERY);
+        $this->assertIsString($query);
         parse_str($query, $params);
-        $this->assertEquals($params['provider_hint'], 'google');
-        $this->assertEquals($params['scope'], 'openid profile');
-        $this->assertEquals($params['code_challenge_method'], 'S256');
-        $this->assertEquals($params['login_hint'], 'user@example.com');
+        $this->assertEquals('google', $params['provider_hint']);
+        $this->assertEquals('openid profile', $params['scope']);
+        $this->assertEquals('S256', $params['code_challenge_method']);
+        $this->assertEquals('user@example.com', $params['login_hint']);
         //$this->assertEquals('https://wallet.hello.coop/authorize?client_id=valid_client_id&redirect_uri=https%3A%2F%2Fexample.com%2Fcallback&scope=openid&response_type=code&response_mode=query&nonce=1234&prompt=consent&code_challenge=yyhvlwTA3oVJcnTpkLV70DjqXb794Ar5Sgth12qbRsM&code_challenge_method=S256&provider_hint=google&login_hint=user%40example.com&domain_hint=example.com', $url);
     }
 
-    public function testGenerateLoginUrlMissingClientId()
+    public function testGenerateLoginUrlMissingClientId(): void
     {
         $_GET = [
             'provider_hint' => 'google',
@@ -98,7 +99,7 @@ public function testGenerateLoginUrlMissingClientId()
         $this->login->generateLoginUrl();
     }
 
-    public function testGenerateLoginUrlMissingRedirectURI()
+    public function testGenerateLoginUrlMissingRedirectURI(): void
     {
         $_GET = [
             'provider_hint' => 'google',
diff --git a/tests/HelloClientTest.php b/tests/HelloClientTest.php
index efd3a36..2d59284 100644
--- a/tests/HelloClientTest.php
+++ b/tests/HelloClientTest.php
@@ -14,9 +14,9 @@ class HelloClientTest extends TestCase
 {
     use ServiceMocksTrait;
 
-    /** @var MockObject|PageRendererInterface */
+    /** @var MockObject & PageRendererInterface */
     private $pageRendererMock;
-    /** @var MockObject|Callback */
+    /** @var MockObject & Callback */
     private $callbackMock;
     private HelloClient $client;
 
@@ -40,7 +40,7 @@ protected function setUp(): void
         $this->pageRendererMock->method('renderErrorPage')->willReturn("error_page");
     }
 
-    public function testRouteHandlesAuth()
+    public function testRouteHandlesAuth(): void
     {
         // Simulate $_GET parameters
         $_GET = ['op' => 'auth'];
@@ -61,7 +61,7 @@ public function testRouteHandlesAuth()
         $this->assertSame('auth_response', $result);
     }
 
-    public function testRouteHandlesCallback()
+    public function testRouteHandlesCallback(): void
     {
         // Simulate $_GET parameters
         $_GET = ['code' => 'callback_code'];
@@ -88,7 +88,7 @@ public function testRouteHandlesCallback()
         $this->assertSame('/dashboard', $result);
     }
 
-    public function testRouteHandlesCallbackException()
+    public function testRouteHandlesCallbackException(): void
     {
         // Simulate $_GET parameters
         $_GET = ['code' => 'callback_code'];
diff --git a/tests/HelloRequest/HelloRequestTest.php b/tests/HelloRequest/HelloRequestTest.php
index e8522d9..365085d 100644
--- a/tests/HelloRequest/HelloRequestTest.php
+++ b/tests/HelloRequest/HelloRequestTest.php
@@ -14,26 +14,26 @@ protected function setUp(): void
         $this->request = new HelloRequest();
     }
 
-    public function testFetchReturnsGetParameter()
+    public function testFetchReturnsGetParameter(): void
     {
         $_GET['test'] = 'value';
         $this->assertSame('value', $this->request->fetch('test'));
     }
 
-    public function testFetchReturnsPostParameterIfGetNotSet()
+    public function testFetchReturnsPostParameterIfGetNotSet(): void
     {
         unset($_GET['test']);
         $_POST['test'] = 'value';
         $this->assertSame('value', $this->request->fetch('test'));
     }
 
-    public function testFetchReturnsDefaultIfNeitherGetNorPostIsSet()
+    public function testFetchReturnsDefaultIfNeitherGetNorPostIsSet(): void
     {
         unset($_GET['test'], $_POST['test']);
         $this->assertSame('default', $this->request->fetch('test', 'default'));
     }
 
-    public function testFetchMultipleReturnsCorrectValues()
+    public function testFetchMultipleReturnsCorrectValues(): void
     {
         $_GET = ['key1' => 'value1'];
         $_POST = ['key2' => 'value2'];
@@ -47,28 +47,28 @@ public function testFetchMultipleReturnsCorrectValues()
         ], $result);
     }
 
-    public function testFetchHeaderReturnsHeaderValue()
+    public function testFetchHeaderReturnsHeaderValue(): void
     {
         $_SERVER['HTTP_TEST_HEADER'] = 'HeaderValue';
 
         $this->assertSame('HeaderValue', $this->request->fetchHeader('Test-Header'));
     }
 
-    public function testFetchHeaderReturnsDefaultIfHeaderNotSet()
+    public function testFetchHeaderReturnsDefaultIfHeaderNotSet(): void
     {
         unset($_SERVER['HTTP_TEST_HEADER']);
 
         $this->assertSame('default', $this->request->fetchHeader('Test-Header', 'default'));
     }
 
-    public function testGetCookieReturnsCookieValue()
+    public function testGetCookieReturnsCookieValue(): void
     {
         $_COOKIE['test_cookie'] = 'cookie_value';
 
         $this->assertSame('cookie_value', $this->request->getCookie('test_cookie'));
     }
 
-    public function testGetCookieReturnsNullIfCookieNotSet()
+    public function testGetCookieReturnsNullIfCookieNotSet(): void
     {
         unset($_COOKIE['test_cookie']);
 
diff --git a/tests/HelloResponse/HelloResponseTest.php b/tests/HelloResponse/HelloResponseTest.php
index b26e714..e999eab 100644
--- a/tests/HelloResponse/HelloResponseTest.php
+++ b/tests/HelloResponse/HelloResponseTest.php
@@ -17,7 +17,7 @@ protected function setUp(): void
         $this->response = new HelloResponse();
     }
 
-    public function testSetHeader()
+    public function testSetHeader(): void
     {
         $headerMock = $this->getFunctionMock('HelloCoop\HelloResponse', 'header');
         $headerMock->expects($this->once())
@@ -26,7 +26,7 @@ public function testSetHeader()
         $this->response->setHeader('Content-Type', 'application/json');
     }
 
-    public function testSetHeaderWithArrayValue()
+    public function testSetHeaderWithArrayValue(): void
     {
         $headerMock = $this->getFunctionMock('HelloCoop\HelloResponse', 'header');
         $headerMock->expects($this->once())
@@ -35,7 +35,7 @@ public function testSetHeaderWithArrayValue()
         $this->response->setHeader('X-Custom-Header', ['value1', 'value2']);
     }
 
-    public function testSetCookie()
+    public function testSetCookie(): void
     {
         $setCookieMock = $this->getFunctionMock('HelloCoop\HelloResponse', 'setcookie');
         $setCookieMock->expects($this->once())
@@ -55,7 +55,7 @@ public function testSetCookie()
         $this->response->setCookie('test_cookie', 'test_value');
     }
 
-    public function testDeleteCookie()
+    public function testDeleteCookie(): void
     {
         $setCookieMock = $this->getFunctionMock('HelloCoop\HelloResponse', 'setcookie');
         $setCookieMock->expects($this->once())
@@ -70,7 +70,7 @@ public function testDeleteCookie()
         $this->response->deleteCookie('delete_cookie');
     }
 
-    public function testRedirect()
+    public function testRedirect(): void
     {
         // Mock the header function
         $headerMock = $this->getFunctionMock('HelloCoop\HelloResponse', 'header');
diff --git a/tests/Lib/AuthHelperTest.php b/tests/Lib/AuthHelperTest.php
index 5ee5e2f..360091a 100644
--- a/tests/Lib/AuthHelperTest.php
+++ b/tests/Lib/AuthHelperTest.php
@@ -12,7 +12,7 @@ class AuthHelperTest extends TestCase
 {
     private AuthHelper $authHelper;
 
-   /** @var MockObject|PKCE */
+   /** @var MockObject & PKCE */
     private $pkceMock;
 
     protected function setUp(): void
@@ -78,18 +78,4 @@ public function testAddDefaultsToScopes(): void
         $result = $this->authHelper->createAuthRequest($config);
         $this->assertStringContainsString('openid', $result['url']);
     }
-
-    private function mockStaticMethod($class, $method, $returnValue): void
-    {
-        $mock = $this->getMockBuilder($class)
-            ->disableOriginalConstructor()
-            ->onlyMethods([$method])
-            ->getMock();
-
-        $mock->method($method)->willReturn($returnValue);
-
-        $refClass = new \ReflectionClass($class);
-        $method = $refClass->getMethod('setMocked');
-        $method->setAccessible(true);
-    }
 }
diff --git a/tests/Lib/OIDCManagerTest.php b/tests/Lib/OIDCManagerTest.php
index 7e887fb..6fe55ad 100644
--- a/tests/Lib/OIDCManagerTest.php
+++ b/tests/Lib/OIDCManagerTest.php
@@ -13,15 +13,15 @@
 
 class OIDCManagerTest extends TestCase
 {
-    /** @var MockObject|HelloRequestInterface */
+    /** @var MockObject & HelloRequestInterface */
     private $helloRequestMock;
-    /** @var MockObject|HelloResponseInterface */
+    /** @var MockObject & HelloResponseInterface */
     private $helloResponseMock;
-    /** @var MockObject|Crypto */
+    /** @var MockObject & Crypto */
     private $cryptoMock;
     /** @var OIDCManager */
     private OIDCManager $oidcManager;
-    /** @var MockObject|ConfigInterface */
+    /** @var MockObject & ConfigInterface */
     private $configMock;
 
     protected function setUp(): void
diff --git a/tests/Lib/TokenParserTest.php b/tests/Lib/TokenParserTest.php
index 695facf..a9f5866 100644
--- a/tests/Lib/TokenParserTest.php
+++ b/tests/Lib/TokenParserTest.php
@@ -7,14 +7,14 @@
 
 class TokenParserTest extends TestCase
 {
-    protected $tokenParser;
+    protected TokenParser $tokenParser;
 
     protected function setUp(): void
     {
         // Initialize the PKCE instance here
         $this->tokenParser = new TokenParser();
     }
-    public function testParseTokenSuccess()
+    public function testParseTokenSuccess(): void
     {
 
         $token = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiZXhwIjoxNjU0MjA4ODAwfQ.sflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c';
@@ -24,11 +24,12 @@ public function testParseTokenSuccess()
         $this->assertIsArray($result);
         $this->assertArrayHasKey('header', $result);
         $this->assertArrayHasKey('payload', $result);
+        $this->assertIsArray($result['payload']);
         $this->assertArrayHasKey('sub', $result['payload']);
         $this->assertArrayHasKey('exp', $result['payload']);
     }
 
-    public function testParseTokenInvalidJson()
+    public function testParseTokenInvalidJson(): void
     {
         $invalidToken = 'invalid.token.format';
 
@@ -38,7 +39,7 @@ public function testParseTokenInvalidJson()
         $this->tokenParser->parseToken($invalidToken);
     }
 
-    public function testParseTokenInvalidFormat()
+    public function testParseTokenInvalidFormat(): void
     {
         $invalidToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9';
 
diff --git a/tests/Traits/ServiceMocksTrait.php b/tests/Traits/ServiceMocksTrait.php
index d13160f..ddb6584 100644
--- a/tests/Traits/ServiceMocksTrait.php
+++ b/tests/Traits/ServiceMocksTrait.php
@@ -12,22 +12,22 @@
 
 trait ServiceMocksTrait
 {
-    /** @var MockObject|HelloRequestInterface */
+    /** @var MockObject & HelloRequestInterface */
     protected $helloRequestMock;
 
-    /** @var MockObject|HelloResponseInterface */
+    /** @var MockObject & HelloResponseInterface */
     protected $helloResponseMock;
 
-    /** @var MockObject|ConfigInterface */
+    /** @var MockObject & ConfigInterface */
     protected $configMock;
 
     /** @var Crypto */
     protected Crypto $crypto;
 
-    /** @var MockObject|TokenFetcher */
+    /** @var MockObject & TokenFetcher */
     protected $tokenFetcherMock;
 
-    /** @var MockObject|TokenParser */
+    /** @var MockObject & TokenParser */
     protected $tokenParserMock;
 
     /**
@@ -89,6 +89,12 @@ protected function setUpServiceMocks(): void
         $_SERVER['REQUEST_METHOD'] = 'GET';
     }
 
+    /**
+     * @param object $object
+     * @param string $propertyName
+     * @param mixed $mock
+     * @return void
+     */
     private function replaceLazyLoadedProperty(object $object, string $propertyName, $mock): void
     {
         $reflection = new \ReflectionClass($object);
diff --git a/tests/Type/AuthTest.php b/tests/Type/AuthTest.php
index 8d480d7..05bbf94 100644
--- a/tests/Type/AuthTest.php
+++ b/tests/Type/AuthTest.php
@@ -36,6 +36,8 @@ public function testAuthCookieProperties(): void
 
         $auth = new Auth(true, $authCookie);
 
+        $this->assertNotNull($auth->authCookie);
+        $this->assertNotNull($auth->authCookie->sub);
         $this->assertSame('user123', $auth->authCookie->sub);
         $this->assertSame('admin', $auth->authCookie->getExtraProperty('role'));
     }
diff --git a/tests/Utils/QueryParamFetcherTest.php b/tests/Utils/QueryParamFetcherTest.php
index c47e187..3d461d9 100644
--- a/tests/Utils/QueryParamFetcherTest.php
+++ b/tests/Utils/QueryParamFetcherTest.php
@@ -7,7 +7,9 @@
 
 class QueryParamFetcherTest extends TestCase
 {
+    /** @var array<string, mixed> $originalGet */
     protected array $originalGet;
+
     protected function setUp(): void
     {
         // Backup the original $_GET superglobal
@@ -20,7 +22,7 @@ protected function tearDown(): void
         $_GET = $this->originalGet;
     }
 
-    public function testFetchWithExistingKeys()
+    public function testFetchWithExistingKeys(): void
     {
         $_GET = [
             'key1' => 'value1',
@@ -35,7 +37,7 @@ public function testFetchWithExistingKeys()
         ], $result);
     }
 
-    public function testFetchWithNonExistentKeys()
+    public function testFetchWithNonExistentKeys(): void
     {
         $_GET = [
             'key1' => 'value1',
@@ -49,7 +51,7 @@ public function testFetchWithNonExistentKeys()
         ], $result);
     }
 
-    public function testFetchWithMixedKeys()
+    public function testFetchWithMixedKeys(): void
     {
         $_GET = [
             'key1' => 'value1',