diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index e168d676..ffa9f6cd 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -4,6 +4,7 @@ use PhpCsFixer\Config;
 use PhpCsFixer\Finder;
 
 $rules = [
+    'nullable_type_declaration_for_default_null_value' => true,
     'single_line_empty_body' => true,
     'array_syntax' => ['syntax' => 'short'],
     'binary_operator_spaces' => [
diff --git a/src/Commands/Install.php b/src/Commands/Install.php
index c7041a72..09e720bb 100644
--- a/src/Commands/Install.php
+++ b/src/Commands/Install.php
@@ -74,12 +74,12 @@ class Install extends Command
      */
     protected function step(
         string $name,
-        Closure $task = null,
+        ?Closure $task = null,
         bool $unless = false,
-        string $warning = null,
-        string $file = null,
-        string $tag = null,
-        array $files = null,
+        ?string $warning = null,
+        ?string $file = null,
+        ?string $tag = null,
+        ?array $files = null,
         bool $newLineBefore = false,
         bool $newLineAfter = false,
     ): void {
diff --git a/src/Controllers/TenantAssetController.php b/src/Controllers/TenantAssetController.php
index add14545..6133c4ce 100644
--- a/src/Controllers/TenantAssetController.php
+++ b/src/Controllers/TenantAssetController.php
@@ -42,7 +42,7 @@ class TenantAssetController implements HasMiddleware
     /**
      * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
      */
-    public function __invoke(Request $request, string $path = null): BinaryFileResponse
+    public function __invoke(Request $request, ?string $path = null): BinaryFileResponse
     {
         $this->validatePath($path);
 
diff --git a/src/Features/UserImpersonation.php b/src/Features/UserImpersonation.php
index ce6687b0..e2a0e69f 100644
--- a/src/Features/UserImpersonation.php
+++ b/src/Features/UserImpersonation.php
@@ -30,7 +30,7 @@ class UserImpersonation implements Feature
     }
 
     /** Impersonate a user and get an HTTP redirect response. */
-    public static function makeResponse(string|ImpersonationToken $token, int $ttl = null): RedirectResponse
+    public static function makeResponse(string|ImpersonationToken $token, ?int $ttl = null): RedirectResponse
     {
         /** @var ImpersonationToken $token */
         $token = $token instanceof ImpersonationToken ? $token : ImpersonationToken::findOrFail($token);
diff --git a/src/Tenancy.php b/src/Tenancy.php
index e30c490f..8b30aa39 100644
--- a/src/Tenancy.php
+++ b/src/Tenancy.php
@@ -151,7 +151,7 @@ class Tenancy
     /**
      * Try to find a tenant using an ID.
      */
-    public static function find(int|string $id, string $column = null, bool $withRelations = false): (Tenant&Model)|null
+    public static function find(int|string $id, ?string $column = null, bool $withRelations = false): (Tenant&Model)|null
     {
         /** @var (Tenant&Model)|null $tenant */
         $tenant = static::model()->with($withRelations ? static::$findWith : [])->firstWhere($column ?? static::model()->getTenantKeyName(), $id);
diff --git a/src/helpers.php b/src/helpers.php
index 333c2829..e42c45c5 100644
--- a/src/helpers.php
+++ b/src/helpers.php
@@ -20,7 +20,7 @@ if (! function_exists('tenant')) {
      *
      * @return Tenant|null|mixed
      */
-    function tenant(string $key = null): mixed
+    function tenant(?string $key = null): mixed
     {
         if (! app()->bound(Tenant::class)) {
             return null;