diff --git a/overrides/Runner/ResultCache/DefaultResultCache.php b/overrides/Runner/ResultCache/DefaultResultCache.php
index 49cdd14c..b798351d 100644
--- a/overrides/Runner/ResultCache/DefaultResultCache.php
+++ b/overrides/Runner/ResultCache/DefaultResultCache.php
@@ -86,7 +86,7 @@ final class DefaultResultCache implements ResultCache
      */
     private array $times = [];
 
-    public function __construct(string $filepath = null)
+    public function __construct(?string $filepath = null)
     {
         if ($filepath !== null && is_dir($filepath)) {
             $filepath .= DIRECTORY_SEPARATOR.self::DEFAULT_RESULT_CACHE_FILENAME;
diff --git a/src/Expectation.php b/src/Expectation.php
index 9a327efa..4f524692 100644
--- a/src/Expectation.php
+++ b/src/Expectation.php
@@ -190,7 +190,7 @@ final class Expectation
      *
      * @return EachExpectation<TValue>
      */
-    public function each(callable $callback = null): EachExpectation
+    public function each(?callable $callback = null): EachExpectation
     {
         if (! is_iterable($this->value)) {
             throw new BadMethodCallException('Expectation value is not iterable.');
diff --git a/src/Functions.php b/src/Functions.php
index 465f3add..34595794 100644
--- a/src/Functions.php
+++ b/src/Functions.php
@@ -55,7 +55,7 @@ if (! function_exists('beforeEach')) {
      *
      * @return HigherOrderTapProxy<Expectable|TestCall|TestCase>|Expectable|TestCall|TestCase|mixed
      */
-    function beforeEach(Closure $closure = null): BeforeEachCall
+    function beforeEach(?Closure $closure = null): BeforeEachCall
     {
         $filename = Backtrace::file();
 
@@ -116,7 +116,7 @@ if (! function_exists('test')) {
      *
      * @return Expectable|TestCall|TestCase|mixed
      */
-    function test(string $description = null, Closure $closure = null): HigherOrderTapProxy|TestCall
+    function test(?string $description = null, ?Closure $closure = null): HigherOrderTapProxy|TestCall
     {
         if ($description === null && TestSuite::getInstance()->test instanceof \PHPUnit\Framework\TestCase) {
             return new HigherOrderTapProxy(TestSuite::getInstance()->test);
@@ -136,7 +136,7 @@ if (! function_exists('it')) {
      *
      * @return Expectable|TestCall|TestCase|mixed
      */
-    function it(string $description, Closure $closure = null): TestCall
+    function it(string $description, ?Closure $closure = null): TestCall
     {
         $description = sprintf('it %s', $description);
 
@@ -171,7 +171,7 @@ if (! function_exists('afterEach')) {
      *
      * @return Expectable|HigherOrderTapProxy<Expectable|TestCall|TestCase>|TestCall|mixed
      */
-    function afterEach(Closure $closure = null): AfterEachCall
+    function afterEach(?Closure $closure = null): AfterEachCall
     {
         $filename = Backtrace::file();
 
diff --git a/src/Logging/TeamCity/ServiceMessage.php b/src/Logging/TeamCity/ServiceMessage.php
index 1f3f2edf..ace7f40b 100644
--- a/src/Logging/TeamCity/ServiceMessage.php
+++ b/src/Logging/TeamCity/ServiceMessage.php
@@ -106,7 +106,7 @@ final class ServiceMessage
         ]);
     }
 
-    public static function testIgnored(string $name, string $message, string $details = null): self
+    public static function testIgnored(string $name, string $message, ?string $details = null): self
     {
         return new self('testIgnored', [
             'name' => $name,
diff --git a/src/Mixins/Expectation.php b/src/Mixins/Expectation.php
index a9edcf07..9b1e07a8 100644
--- a/src/Mixins/Expectation.php
+++ b/src/Mixins/Expectation.php
@@ -920,7 +920,7 @@ final class Expectation
      * @param  (Closure(Throwable): mixed)|string  $exception
      * @return self<TValue>
      */
-    public function toThrow(callable|string|Throwable $exception, string $exceptionMessage = null, string $message = ''): self
+    public function toThrow(callable|string|Throwable $exception, ?string $exceptionMessage = null, string $message = ''): self
     {
         $callback = NullClosure::create();
 
diff --git a/src/PendingCalls/AfterEachCall.php b/src/PendingCalls/AfterEachCall.php
index 9a22258e..a20157e9 100644
--- a/src/PendingCalls/AfterEachCall.php
+++ b/src/PendingCalls/AfterEachCall.php
@@ -35,7 +35,7 @@ final class AfterEachCall
     public function __construct(
         private readonly TestSuite $testSuite,
         private readonly string $filename,
-        Closure $closure = null
+        ?Closure $closure = null
     ) {
         $this->closure = $closure instanceof Closure ? $closure : NullClosure::create();
 
diff --git a/src/PendingCalls/BeforeEachCall.php b/src/PendingCalls/BeforeEachCall.php
index 200c4fa9..2be5510d 100644
--- a/src/PendingCalls/BeforeEachCall.php
+++ b/src/PendingCalls/BeforeEachCall.php
@@ -40,7 +40,7 @@ final class BeforeEachCall
     public function __construct(
         public readonly TestSuite $testSuite,
         private readonly string $filename,
-        Closure $closure = null
+        ?Closure $closure = null
     ) {
         $this->closure = $closure instanceof Closure ? $closure : NullClosure::create();
 
diff --git a/src/PendingCalls/TestCall.php b/src/PendingCalls/TestCall.php
index 07053131..3586cdcc 100644
--- a/src/PendingCalls/TestCall.php
+++ b/src/PendingCalls/TestCall.php
@@ -51,8 +51,8 @@ final class TestCall
     public function __construct(
         private readonly TestSuite $testSuite,
         private readonly string $filename,
-        string $description = null,
-        Closure $closure = null
+        ?string $description = null,
+        ?Closure $closure = null
     ) {
         $this->testCaseMethod = new TestCaseMethodFactory($filename, $description, $closure);
 
@@ -66,7 +66,7 @@ final class TestCall
     /**
      * Asserts that the test fails with the given message.
      */
-    public function fails(string $message = null): self
+    public function fails(?string $message = null): self
     {
         return $this->throws(AssertionFailedError::class, $message);
     }
@@ -74,7 +74,7 @@ final class TestCall
     /**
      * Asserts that the test throws the given `$exceptionClass` when called.
      */
-    public function throws(string|int $exception, string $exceptionMessage = null, int $exceptionCode = null): self
+    public function throws(string|int $exception, ?string $exceptionMessage = null, ?int $exceptionCode = null): self
     {
         if (is_int($exception)) {
             $exceptionCode = $exception;
@@ -106,7 +106,7 @@ final class TestCall
      *
      * @param  (callable(): bool)|bool  $condition
      */
-    public function throwsIf(callable|bool $condition, string|int $exception, string $exceptionMessage = null, int $exceptionCode = null): self
+    public function throwsIf(callable|bool $condition, string|int $exception, ?string $exceptionMessage = null, ?int $exceptionCode = null): self
     {
         $condition = is_callable($condition)
             ? $condition
@@ -124,7 +124,7 @@ final class TestCall
      *
      * @param  (callable(): bool)|bool  $condition
      */
-    public function throwsUnless(callable|bool $condition, string|int $exception, string $exceptionMessage = null, int $exceptionCode = null): self
+    public function throwsUnless(callable|bool $condition, string|int $exception, ?string $exceptionMessage = null, ?int $exceptionCode = null): self
     {
         $condition = is_callable($condition)
             ? $condition
@@ -401,7 +401,7 @@ final class TestCall
      *
      * @param  array<int, mixed>|null  $arguments
      */
-    private function addChain(string $file, int $line, string $name, array $arguments = null): self
+    private function addChain(string $file, int $line, string $name, ?array $arguments = null): self
     {
         $exporter = Exporter::default();
 
diff --git a/src/Plugins/Environment.php b/src/Plugins/Environment.php
index aebe2343..8ff10b4c 100644
--- a/src/Plugins/Environment.php
+++ b/src/Plugins/Environment.php
@@ -45,7 +45,7 @@ final class Environment implements HandlesArguments
     /**
      * Gets the environment name.
      */
-    public static function name(string $name = null): string
+    public static function name(?string $name = null): string
     {
         if (is_string($name)) {
             self::$name = $name;
diff --git a/src/Support/Exporter.php b/src/Support/Exporter.php
index 313d081f..ea02ce61 100644
--- a/src/Support/Exporter.php
+++ b/src/Support/Exporter.php
@@ -41,7 +41,7 @@ final class Exporter
      *
      * @param  array<int|string, mixed>  $data
      */
-    public function shortenedRecursiveExport(array &$data, Context $context = null): string
+    public function shortenedRecursiveExport(array &$data, ?Context $context = null): string
     {
         $result = [];
         $array = $data;
diff --git a/src/TestSuite.php b/src/TestSuite.php
index 885baa2f..496eb0ce 100644
--- a/src/TestSuite.php
+++ b/src/TestSuite.php
@@ -87,8 +87,8 @@ final class TestSuite
      * Returns the current instance of the test suite.
      */
     public static function getInstance(
-        string $rootPath = null,
-        string $testPath = null,
+        ?string $rootPath = null,
+        ?string $testPath = null,
     ): TestSuite {
         if (is_string($rootPath) && is_string($testPath)) {
             self::$instance = new TestSuite($rootPath, $testPath);