diff --git a/.github/workflows/bc.yml b/.github/workflows/bc.yml
index f8cc564..0ea4a5c 100644
--- a/.github/workflows/bc.yml
+++ b/.github/workflows/bc.yml
@@ -30,4 +30,4 @@ jobs:
       os: >-
         ['ubuntu-latest']
       php: >-
-        ['8.0']
+        ['8.4']
diff --git a/.github/workflows/mutation.yml b/.github/workflows/mutation.yml
index 8150499..a56769e 100644
--- a/.github/workflows/mutation.yml
+++ b/.github/workflows/mutation.yml
@@ -27,6 +27,6 @@ jobs:
       os: >-
         ['ubuntu-latest']
       php: >-
-        ['8.2']
+        ['8.4']
     secrets:
       STRYKER_DASHBOARD_API_KEY: ${{ secrets.STRYKER_DASHBOARD_API_KEY }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 438f228..ba33717 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ## 2.2.2 under development
 
-- no changes in this release.
+- Bug #79: Explicitly marking parameters as nullable (@Tigrov)
 
 ## 2.2.1 March 05, 2025
 
diff --git a/composer.json b/composer.json
index 01f2725..d9889d3 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
         }
     ],
     "require": {
-        "php": "~7.4.0 || ~8.0.0 || ~8.1.0 || ~8.2.0 || ~8.3.0 || ~8.4.0",
+        "php": "~7.4.0 || 8.0 - 8.4",
         "ext-hash": "*",
         "psr/http-factory": "^1.0",
         "psr/http-factory-implementation": "1.0",
@@ -48,8 +48,8 @@
     "require-dev": {
         "maglnet/composer-require-checker": "^3.8 || ^4.2",
         "nyholm/psr7": "^1.8.2",
-        "phpunit/phpunit": "^9.6.22",
-        "rector/rector": "^2.0.9",
+        "phpunit/phpunit": "^9.6.23",
+        "rector/rector": "^2.0.16",
         "roave/infection-static-analysis-plugin": "^1.18",
         "spatie/phpunit-watcher": "^1.23.6",
         "vimeo/psalm": "^4.30 || ^5.26.1 || ^6.8.8",
@@ -76,7 +76,6 @@
     },
     "config": {
         "sort-packages": true,
-        "bump-after-update": "dev",
         "allow-plugins": {
             "infection/extension-installer": true,
             "composer/package-versions-deprecated": true
diff --git a/src/CsrfHeaderMiddleware.php b/src/CsrfHeaderMiddleware.php
index b820594..1c91ffd 100644
--- a/src/CsrfHeaderMiddleware.php
+++ b/src/CsrfHeaderMiddleware.php
@@ -37,7 +37,7 @@ final class CsrfHeaderMiddleware implements MiddlewareInterface
 
     public function __construct(
         ResponseFactoryInterface $responseFactory,
-        RequestHandlerInterface $failureHandler = null
+        ?RequestHandlerInterface $failureHandler = null
     ) {
         $this->responseFactory = $responseFactory;
         $this->failureHandler = $failureHandler;
diff --git a/src/CsrfMiddleware.php b/src/CsrfMiddleware.php
index 038a820..ae886fe 100644
--- a/src/CsrfMiddleware.php
+++ b/src/CsrfMiddleware.php
@@ -42,7 +42,7 @@ final class CsrfMiddleware implements MiddlewareInterface
     public function __construct(
         ResponseFactoryInterface $responseFactory,
         CsrfTokenInterface $token,
-        RequestHandlerInterface $failureHandler = null
+        ?RequestHandlerInterface $failureHandler = null
     ) {
         $this->responseFactory = $responseFactory;
         $this->token = $token;
diff --git a/src/CsrfTokenMiddleware.php b/src/CsrfTokenMiddleware.php
index f55d49d..1401b11 100644
--- a/src/CsrfTokenMiddleware.php
+++ b/src/CsrfTokenMiddleware.php
@@ -41,7 +41,7 @@ final class CsrfTokenMiddleware implements MiddlewareInterface
     public function __construct(
         ResponseFactoryInterface $responseFactory,
         CsrfTokenInterface $token,
-        RequestHandlerInterface $failureHandler = null
+        ?RequestHandlerInterface $failureHandler = null
     ) {
         $this->responseFactory = $responseFactory;
         $this->token = $token;
diff --git a/tests/CsrfHeaderMiddlewareProcessTest.php b/tests/CsrfHeaderMiddlewareProcessTest.php
index 8ee926b..ccc54d6 100644
--- a/tests/CsrfHeaderMiddlewareProcessTest.php
+++ b/tests/CsrfHeaderMiddlewareProcessTest.php
@@ -146,7 +146,7 @@ public function handle(ServerRequestInterface $request): ResponseInterface
     }
 
     private function createMiddleware(
-        RequestHandlerInterface $failureHandler = null
+        ?RequestHandlerInterface $failureHandler = null
     ): CsrfHeaderMiddleware {
         return new CsrfHeaderMiddleware(new Psr17Factory(), $failureHandler);
     }
diff --git a/tests/CsrfTokenMiddlewareProcessTest.php b/tests/CsrfTokenMiddlewareProcessTest.php
index 66c8763..f11c890 100644
--- a/tests/CsrfTokenMiddlewareProcessTest.php
+++ b/tests/CsrfTokenMiddlewareProcessTest.php
@@ -232,7 +232,7 @@ private function getBodyRequestParamsByToken(string $token): array
 
     protected function createCsrfTokenMiddleware(
         ?CsrfTokenInterface $csrfToken = null,
-        RequestHandlerInterface $failureHandler = null
+        ?RequestHandlerInterface $failureHandler = null
     ): CsrfTokenMiddleware {
         $csrfToken = new MaskedCsrfToken($csrfToken ?? $this->createCsrfToken());
         $this->token = $csrfToken->getValue();
diff --git a/tests/DeprecatedTokenCsrfMiddlewareTest.php b/tests/DeprecatedTokenCsrfMiddlewareTest.php
index 0ccbb48..18c9117 100644
--- a/tests/DeprecatedTokenCsrfMiddlewareTest.php
+++ b/tests/DeprecatedTokenCsrfMiddlewareTest.php
@@ -232,7 +232,7 @@ private function getBodyRequestParamsByToken(string $token): array
 
     protected function createCsrfMiddleware(
         ?CsrfTokenInterface $csrfToken = null,
-        RequestHandlerInterface $failureHandler = null
+        ?RequestHandlerInterface $failureHandler = null
     ): CsrfMiddleware {
         $csrfToken = new MaskedCsrfToken($csrfToken ?? $this->createCsrfToken());
         $this->token = $csrfToken->getValue();
diff --git a/tests/MaskedCsrfTokenTest.php b/tests/MaskedCsrfTokenTest.php
index c794701..35361e5 100644
--- a/tests/MaskedCsrfTokenTest.php
+++ b/tests/MaskedCsrfTokenTest.php
@@ -19,7 +19,7 @@ public function testBase(): void
         $this->assertSame('test_token', TokenMask::remove($csrfToken->getValue()));
     }
 
-    private function createCsrfToken(string $token = null): MaskedCsrfToken
+    private function createCsrfToken(?string $token = null): MaskedCsrfToken
     {
         $mock = $this->createMock(MockCsrfTokenStorage::class);
         if ($token !== null) {