diff --git a/src/Exceptions/PhpK8sException.php b/src/Exceptions/PhpK8sException.php
index a9270518dabf1b14ec0f6f889dfc9b69fad19248..f6611b4aac8dd60f130ed063ae1588ac8ef72639 100644
--- a/src/Exceptions/PhpK8sException.php
+++ b/src/Exceptions/PhpK8sException.php
@@ -20,7 +20,7 @@ class PhpK8sException extends Exception
      * @param  int  $code
      * @param  array|null  $payload
      */
-    public function __construct($message = null, $code = 0, array $payload = null)
+    public function __construct($message = null, $code = 0, ?array $payload = null)
     {
         parent::__construct($message, $code);
 
diff --git a/src/Instances/Container.php b/src/Instances/Container.php
index 4e8c29fa96b7a7518b716e94e4fecc9f7f652350..4c4f34edd8cd1d11bb9df87b1487ee6080be8aff 100644
--- a/src/Instances/Container.php
+++ b/src/Instances/Container.php
@@ -24,7 +24,7 @@ class Container extends Instance
      * @param  string  $name
      * @return $this
      */
-    public function addPort(int $containerPort, string $protocol = 'TCP', string $name = null)
+    public function addPort(int $containerPort, string $protocol = 'TCP', ?string $name = null)
     {
         return $this->addToAttribute('ports', [
             'name' => $name,
diff --git a/src/Instances/MountedVolume.php b/src/Instances/MountedVolume.php
index 7d36b5689b9e85802fe7a12127662c32a02070bd..18304fc9e5c319c7a338d768b87bdf7e75b025f8 100644
--- a/src/Instances/MountedVolume.php
+++ b/src/Instances/MountedVolume.php
@@ -32,7 +32,7 @@ class MountedVolume extends Instance
      * @param  string|null  $subPath
      * @return $this
      */
-    public function mountTo(string $mountPath, string $subPath = null)
+    public function mountTo(string $mountPath, ?string $subPath = null)
     {
         $this->setMountPath($mountPath);
 
diff --git a/src/Instances/Probe.php b/src/Instances/Probe.php
index 4cb07bc155c63628cbb06e4c213df79502af6b09..4207813ee207eeb2efadd069d6f2ff4797ac2773 100644
--- a/src/Instances/Probe.php
+++ b/src/Instances/Probe.php
@@ -72,7 +72,7 @@ class Probe extends Instance
      * @param  string  $host
      * @return $this
      */
-    public function tcp(int $port, string $host = null)
+    public function tcp(int $port, ?string $host = null)
     {
         if ($host) {
             $this->setAttribute('tcpSocket.host', $host);
diff --git a/src/Instances/Volume.php b/src/Instances/Volume.php
index 956e9e56cc422e899139e62e9ee2807710343b29..1ef5b44419447e3fc8aacff6f228f6921f9dea8c 100644
--- a/src/Instances/Volume.php
+++ b/src/Instances/Volume.php
@@ -77,7 +77,7 @@ class Volume extends Instance
      * @param  string|null  $subPath
      * @return \RenokiCo\PhpK8s\Instances\MountedVolume
      */
-    public function mountTo(string $mountPath, string $subPath = null)
+    public function mountTo(string $mountPath, ?string $subPath = null)
     {
         return MountedVolume::from($this)->mountTo($mountPath, $subPath);
     }
diff --git a/src/K8s.php b/src/K8s.php
index f410a0749120b67ee0f96df7ebe610ce8fd60c70..8718d649477749ce85e6ecfb96c288d55ca3106b 100644
--- a/src/K8s.php
+++ b/src/K8s.php
@@ -57,7 +57,7 @@ class K8s
      * @param  Closure|null  $callback
      * @return \RenokiCo\PhpK8s\Kinds\K8sResource|array[\RenokiCo\PhpK8s\Kinds\K8sResource]
      */
-    public static function fromYamlFile($cluster, string $path, Closure $callback = null)
+    public static function fromYamlFile($cluster, string $path, ?Closure $callback = null)
     {
         $content = file_get_contents($path);
 
@@ -79,7 +79,7 @@ class K8s
      * @param  \Closure|null  $callback
      * @return \RenokiCo\PhpK8s\Kinds\K8sResource|array[\RenokiCo\PhpK8s\Kinds\K8sResource]
      */
-    public static function fromTemplatedYamlFile($cluster, string $path, array $replace, Closure $callback = null)
+    public static function fromTemplatedYamlFile($cluster, string $path, array $replace, ?Closure $callback = null)
     {
         return static::fromYamlFile($cluster, $path, function ($content) use ($replace, $callback) {
             foreach ($replace as $search => $replacement) {
@@ -97,7 +97,7 @@ class K8s
      * @param  string|null  $name
      * @return void
      */
-    public static function registerCrd(string $class, string $name = null): void
+    public static function registerCrd(string $class, ?string $name = null): void
     {
         static::macro(
             Str::camel($name ?: substr($class, strrpos($class, '\\') + 1)),
diff --git a/src/Kinds/K8sConfigMap.php b/src/Kinds/K8sConfigMap.php
index 563afeb9a7d242d05147a95a3f502a92467dae15..f3735ad395249eec6f787b0484c6660ef2471d73 100644
--- a/src/Kinds/K8sConfigMap.php
+++ b/src/Kinds/K8sConfigMap.php
@@ -30,7 +30,7 @@ class K8sConfigMap extends K8sResource implements InteractsWithK8sCluster, Watch
      * @param  string|null  $name
      * @return mixed
      */
-    public function getData(string $name = null)
+    public function getData(?string $name = null)
     {
         if ($name) {
             return $this->getAttribute("data.{$name}", '');
diff --git a/src/Kinds/K8sResource.php b/src/Kinds/K8sResource.php
index 9b325342ccb18c4338bf4b65c84085277390490b..5117e6dafed1f23cc1149b70306fbbf209c5717a 100644
--- a/src/Kinds/K8sResource.php
+++ b/src/Kinds/K8sResource.php
@@ -55,7 +55,7 @@ class K8sResource implements Arrayable, Jsonable
      * @param  string|null  $name
      * @return void
      */
-    public static function register(string $name = null): void
+    public static function register(?string $name = null): void
     {
         K8s::registerCrd(static::class, $name);
     }
@@ -69,7 +69,7 @@ class K8sResource implements Arrayable, Jsonable
      * @param  string|null  $defaultVersion
      * @return string
      */
-    public static function getUniqueCrdMacro(string $kind = null, string $defaultVersion = null): string
+    public static function getUniqueCrdMacro(?string $kind = null, ?string $defaultVersion = null): string
     {
         $kind = $kind ?: static::getKind();
         $defaultVersion = $defaultVersion ?: static::getDefaultVersion();
@@ -127,7 +127,7 @@ class K8sResource implements Arrayable, Jsonable
      * @param  string|null  $kind
      * @return array
      */
-    public function toArray(string $kind = null)
+    public function toArray(?string $kind = null)
     {
         $attributes = $this->attributes;
 
@@ -154,7 +154,7 @@ class K8sResource implements Arrayable, Jsonable
      * @param  string|null  $kind
      * @return string
      */
-    public function toJson($options = 0, string $kind = null)
+    public function toJson($options = 0, ?string $kind = null)
     {
         return json_encode($this->toArray($kind), $options);
     }
@@ -167,7 +167,7 @@ class K8sResource implements Arrayable, Jsonable
      * @param  string|null  $kind
      * @return string
      */
-    public function toJsonPayload(string $kind = null)
+    public function toJsonPayload(?string $kind = null)
     {
         $attributes = $this->toJson(JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES, $kind);
 
diff --git a/src/KubernetesCluster.php b/src/KubernetesCluster.php
index 1c6a7f4ec0a45100311057f041edb59b192b253c..521273ab28a0b945f4820dd40ad3b0975e94e2fa 100644
--- a/src/KubernetesCluster.php
+++ b/src/KubernetesCluster.php
@@ -170,7 +170,7 @@ class KubernetesCluster
      * @param  string|null  $url
      * @return void
      */
-    public function __construct(string $url = null)
+    public function __construct(?string $url = null)
     {
         $this->url = $url;
     }
diff --git a/src/Traits/Cluster/AuthenticatesCluster.php b/src/Traits/Cluster/AuthenticatesCluster.php
index cbe3f6abb415c652b4514ccadbbb820615a52837..3a48bb5f74316360d1543330b82666e8bd1e280b 100644
--- a/src/Traits/Cluster/AuthenticatesCluster.php
+++ b/src/Traits/Cluster/AuthenticatesCluster.php
@@ -65,7 +65,7 @@ trait AuthenticatesCluster
      * @param  string|null  $token
      * @return $this
      */
-    public function withToken(string $token = null)
+    public function withToken(?string $token = null)
     {
         $this->token = $this->normalize($token);
 
@@ -80,7 +80,7 @@ trait AuthenticatesCluster
      * @param  string|null  $tokenPath
      * @return $this
      */
-    public function withTokenFromCommandProvider(string $cmdPath, string $cmdArgs = null, string $tokenPath = null)
+    public function withTokenFromCommandProvider(string $cmdPath, ?string $cmdArgs = null, ?string $tokenPath = null)
     {
         $process = Process::fromShellCommandline("{$cmdPath} {$cmdArgs}");
 
@@ -109,7 +109,7 @@ trait AuthenticatesCluster
      * @param  string|null  $path
      * @return $this
      */
-    public function loadTokenFromFile(string $path = null)
+    public function loadTokenFromFile(?string $path = null)
     {
         return $this->withToken(file_get_contents($path));
     }
@@ -121,7 +121,7 @@ trait AuthenticatesCluster
      * @param  string|null  $password
      * @return $this
      */
-    public function httpAuthentication(string $username = null, string $password = null)
+    public function httpAuthentication(?string $username = null, ?string $password = null)
     {
         if (! is_null($username) || ! is_null($password)) {
             $this->auth = [$username, $password];
@@ -136,7 +136,7 @@ trait AuthenticatesCluster
      * @param  string|null  $path
      * @return $this
      */
-    public function withCertificate(string $path = null)
+    public function withCertificate(?string $path = null)
     {
         $this->cert = $path;
 
@@ -149,7 +149,7 @@ trait AuthenticatesCluster
      * @param  string|null  $path
      * @return $this
      */
-    public function withPrivateKey(string $path = null)
+    public function withPrivateKey(?string $path = null)
     {
         $this->sslKey = $path;
 
@@ -162,7 +162,7 @@ trait AuthenticatesCluster
      * @param  string|null  $path
      * @return $this
      */
-    public function withCaCertificate(string $path = null)
+    public function withCaCertificate(?string $path = null)
     {
         $this->verify = $path;
 
diff --git a/src/Traits/Cluster/LoadsFromKubeConfig.php b/src/Traits/Cluster/LoadsFromKubeConfig.php
index 091b8ec6c885703b5eaf842eb06206781908af26..068e18b588128cfa474bb4166b23c0748922550f 100644
--- a/src/Traits/Cluster/LoadsFromKubeConfig.php
+++ b/src/Traits/Cluster/LoadsFromKubeConfig.php
@@ -44,7 +44,7 @@ trait LoadsFromKubeConfig
      * @throws \RenokiCo\PhpK8s\Exceptions\KubeConfigContextNotFound
      * @throws \RenokiCo\PhpK8s\Exceptions\KubeConfigUserNotFound
      */
-    public static function fromKubeConfigVariable(string $context = null)
+    public static function fromKubeConfigVariable(?string $context = null)
     {
         /** @var \RenokiCo\PhpK8s\KubernetesCluster $this */
         $cluster = new static;
@@ -82,7 +82,7 @@ trait LoadsFromKubeConfig
      * @param  string|null  $context
      * @return \RenokiCo\PhpK8s\KubernetesCluster
      */
-    public static function fromKubeConfigYaml(string $yaml, string $context = null)
+    public static function fromKubeConfigYaml(string $yaml, ?string $context = null)
     {
         /** @var \RenokiCo\PhpK8s\KubernetesCluster $this */
         $cluster = new static;
@@ -97,7 +97,7 @@ trait LoadsFromKubeConfig
      * @param  string|null  $context
      * @return \RenokiCo\PhpK8s\KubernetesCluster
      */
-    public static function fromKubeConfigYamlFile(string $path = '/.kube/config', string $context = null)
+    public static function fromKubeConfigYamlFile(string $path = '/.kube/config', ?string $context = null)
     {
         return (new static)->fromKubeConfigYaml(file_get_contents($path), $context);
     }
@@ -109,7 +109,7 @@ trait LoadsFromKubeConfig
      * @param  string|null  $context
      * @return \RenokiCo\PhpK8s\KubernetesCluster
      */
-    public static function fromKubeConfigArray(array $kubeConfigArray, string $context = null)
+    public static function fromKubeConfigArray(array $kubeConfigArray, ?string $context = null)
     {
         $cluster = new static;
 
@@ -128,7 +128,7 @@ trait LoadsFromKubeConfig
      * @throws \RenokiCo\PhpK8s\Exceptions\KubeConfigContextNotFound
      * @throws \RenokiCo\PhpK8s\Exceptions\KubeConfigUserNotFound
      */
-    protected function loadKubeConfigFromArray(array $kubeconfig, string $context = null)
+    protected function loadKubeConfigFromArray(array $kubeconfig, ?string $context = null)
     {
         /** @var \RenokiCo\PhpK8s\KubernetesCluster $this */
 
diff --git a/src/Traits/Cluster/MakesWebsocketCalls.php b/src/Traits/Cluster/MakesWebsocketCalls.php
index 06d85c3cbca2b0579d442b52709de97605464b98..db97e8407ca7950a558a47cb5a50ca0abe4b2204 100644
--- a/src/Traits/Cluster/MakesWebsocketCalls.php
+++ b/src/Traits/Cluster/MakesWebsocketCalls.php
@@ -143,7 +143,7 @@ trait MakesWebsocketCalls
      * @param  array  $query
      * @return mixed
      */
-    protected function makeWsRequest(string $path, Closure $callback = null, array $query = ['pretty' => 1])
+    protected function makeWsRequest(string $path, ?Closure $callback = null, array $query = ['pretty' => 1])
     {
         $url = $this->getCallableUrl($path, $query);
 
diff --git a/src/Traits/RunsClusterOperations.php b/src/Traits/RunsClusterOperations.php
index 342a1be8c9028b08be00645a3e12ec7261e826be..6403c6081e38cab1ce1faab5e3b64a09bcd1d9c0 100644
--- a/src/Traits/RunsClusterOperations.php
+++ b/src/Traits/RunsClusterOperations.php
@@ -455,7 +455,7 @@ trait RunsClusterOperations
      */
     public function exec(
         $command,
-        string $container = null,
+        ?string $container = null,
         array $query = ['pretty' => 1, 'stdin' => 1, 'stdout' => 1, 'stderr' => 1, 'tty' => 1]
     ) {
         if (! $this instanceof Executable) {
@@ -486,8 +486,8 @@ trait RunsClusterOperations
      * @throws \RenokiCo\PhpK8s\Exceptions\KubernetesAPIException
      */
     public function attach(
-        Closure $callback = null,
-        string $container = null,
+        ?Closure $callback = null,
+        ?string $container = null,
         array $query = ['pretty' => 1, 'stdin' => 1, 'stdout' => 1, 'stderr' => 1, 'tty' => 1]
     ) {
         if (! $this instanceof Attachable) {
@@ -594,7 +594,7 @@ trait RunsClusterOperations
      * @param  string|null  $preNamespaceAction
      * @return string
      */
-    protected function getApiPathPrefix(bool $withNamespace = true, string $preNamespaceAction = null): string
+    protected function getApiPathPrefix(bool $withNamespace = true, ?string $preNamespaceAction = null): string
     {
         $version = $this->getApiVersion();
 
diff --git a/tests/KubeConfigTest.php b/tests/KubeConfigTest.php
index 82a657ecaef15ae88c88d2ba78e1c861f3cf19a2..cc4aa87c38bbd9be375d2d332de07683e9d7d250 100644
--- a/tests/KubeConfigTest.php
+++ b/tests/KubeConfigTest.php
@@ -211,7 +211,7 @@ class KubeConfigTest extends TestCase
     /**
      * @dataProvider environmentVariableContextProvider
      */
-    public function test_from_environment_variable(string $context = null, string $expectedDomain)
+    public function test_from_environment_variable(?string $context = null, string $expectedDomain)
     {
         $_SERVER['KUBECONFIG'] = __DIR__.'/cluster/kubeconfig.yaml::'.__DIR__.'/cluster/kubeconfig-2.yaml';