diff --git a/src/Builder/OpenApiBuilder.php b/src/Builder/OpenApiBuilder.php
index a19e2d4..b131feb 100644
--- a/src/Builder/OpenApiBuilder.php
+++ b/src/Builder/OpenApiBuilder.php
@@ -36,7 +36,7 @@
  */
 class OpenApiBuilder implements OpenApiBuilderInterface
 {
-    public function schema(SchemaConfigurator|ReferenceConfigurator|string $definition = null): SchemaConfigurator|ReferenceConfigurator
+    public function schema(SchemaConfigurator|ReferenceConfigurator|string|null $definition = null): SchemaConfigurator|ReferenceConfigurator
     {
         return SchemaConfigurator::createFromDefinition($definition);
     }
diff --git a/src/Builder/OpenApiBuilderInterface.php b/src/Builder/OpenApiBuilderInterface.php
index ca80601..c928617 100644
--- a/src/Builder/OpenApiBuilderInterface.php
+++ b/src/Builder/OpenApiBuilderInterface.php
@@ -36,7 +36,7 @@
  */
 interface OpenApiBuilderInterface
 {
-    public function schema(SchemaConfigurator|ReferenceConfigurator|string $definition = null): SchemaConfigurator|ReferenceConfigurator;
+    public function schema(SchemaConfigurator|ReferenceConfigurator|string|null $definition = null): SchemaConfigurator|ReferenceConfigurator;
 
     public function callbackRequest(): CallbackRequestConfigurator;
 
diff --git a/src/Configurator/ComponentsConfigurator.php b/src/Configurator/ComponentsConfigurator.php
index 8ebfb6b..663b380 100644
--- a/src/Configurator/ComponentsConfigurator.php
+++ b/src/Configurator/ComponentsConfigurator.php
@@ -29,7 +29,7 @@ class ComponentsConfigurator
     private array $callbacks = [];
     private array $pathItems = [];
 
-    public function build(Components $toMergeWith = null): Components
+    public function build(?Components $toMergeWith = null): Components
     {
         if (!$toMergeWith) {
             $toMergeWith = new Components();
diff --git a/src/Configurator/InfoConfigurator.php b/src/Configurator/InfoConfigurator.php
index 2e12058..418d4d0 100644
--- a/src/Configurator/InfoConfigurator.php
+++ b/src/Configurator/InfoConfigurator.php
@@ -64,14 +64,14 @@ public function termsOfService(string $termsOfService): static
         return $this;
     }
 
-    public function contact(string $name = null, string $url = null, string $email = null, array $specificationExtensions = []): static
+    public function contact(?string $name = null, ?string $url = null, ?string $email = null, array $specificationExtensions = []): static
     {
         $this->contact = new Contact($name, $url, $email, $specificationExtensions);
 
         return $this;
     }
 
-    public function license(string $name, string $identifier = null, string $url = null, array $specificationExtensions = []): static
+    public function license(string $name, ?string $identifier = null, ?string $url = null, array $specificationExtensions = []): static
     {
         $this->license = new License($name, $identifier, $url, $specificationExtensions);
 
diff --git a/src/Configurator/PathItemConfigurator.php b/src/Configurator/PathItemConfigurator.php
index 5c335bb..2839521 100644
--- a/src/Configurator/PathItemConfigurator.php
+++ b/src/Configurator/PathItemConfigurator.php
@@ -41,7 +41,7 @@ public function __construct(OpenApiBuilderInterface $openApiBuilder)
         $this->openApiBuilder = $openApiBuilder;
     }
 
-    public function build(PathItem $toMergeWith = null): PathItem
+    public function build(?PathItem $toMergeWith = null): PathItem
     {
         return new PathItem(
             ref: $this->ref ?: $toMergeWith?->getRef(),
diff --git a/src/Configurator/SchemaConfigurator.php b/src/Configurator/SchemaConfigurator.php
index 3b795e6..60fd000 100644
--- a/src/Configurator/SchemaConfigurator.php
+++ b/src/Configurator/SchemaConfigurator.php
@@ -87,7 +87,7 @@ class SchemaConfigurator
      */
     private ?array $anyOf = null;
 
-    public static function createFromDefinition(self|ReferenceConfigurator|string|array $definition = null): self|ReferenceConfigurator
+    public static function createFromDefinition(self|ReferenceConfigurator|string|array|null $definition = null): self|ReferenceConfigurator
     {
         // Empty schema
         if (!$definition) {
@@ -418,7 +418,7 @@ public function example(mixed $example): static
         return $this;
     }
 
-    public function discriminator(string $propertyName, array $mapping = null, array $specificationExtensions = []): static
+    public function discriminator(string $propertyName, ?array $mapping = null, array $specificationExtensions = []): static
     {
         $this->discriminator = new Discriminator($propertyName, $mapping, $specificationExtensions);
 
@@ -426,11 +426,11 @@ public function discriminator(string $propertyName, array $mapping = null, array
     }
 
     public function xml(
-        string $name = null,
-        string $namespace = null,
-        string $prefix = null,
-        bool $attribute = null,
-        bool $wrapped = null,
+        ?string $name = null,
+        ?string $namespace = null,
+        ?string $prefix = null,
+        ?bool $attribute = null,
+        ?bool $wrapped = null,
         array $specificationExtensions = [],
     ): static {
         $this->xml = new Xml($name, $namespace, $prefix, $attribute, $wrapped, $specificationExtensions);
diff --git a/src/Configurator/Traits/ExamplesTrait.php b/src/Configurator/Traits/ExamplesTrait.php
index 5c42dcb..a8b4cce 100644
--- a/src/Configurator/Traits/ExamplesTrait.php
+++ b/src/Configurator/Traits/ExamplesTrait.php
@@ -27,7 +27,7 @@ trait ExamplesTrait
      */
     private ?array $examples = null;
 
-    public function example(mixed $name, ExampleConfigurator|ReferenceConfigurator $example = null): static
+    public function example(mixed $name, ExampleConfigurator|ReferenceConfigurator|null $example = null): static
     {
         if ($example) {
             $this->examples[$name] = $example->build();
diff --git a/src/Configurator/Traits/ExternalDocsTrait.php b/src/Configurator/Traits/ExternalDocsTrait.php
index 087845d..2e4ffc7 100644
--- a/src/Configurator/Traits/ExternalDocsTrait.php
+++ b/src/Configurator/Traits/ExternalDocsTrait.php
@@ -19,7 +19,7 @@ trait ExternalDocsTrait
 {
     private ?ExternalDocumentation $externalDocs = null;
 
-    public function externalDocs(string $url, string $description = null, array $specificationExtensions = []): static
+    public function externalDocs(string $url, ?string $description = null, array $specificationExtensions = []): static
     {
         $this->externalDocs = new ExternalDocumentation($url, $description, $specificationExtensions);
 
diff --git a/src/Configurator/Traits/ServerVariablesTrait.php b/src/Configurator/Traits/ServerVariablesTrait.php
index 701d065..f6796a6 100644
--- a/src/Configurator/Traits/ServerVariablesTrait.php
+++ b/src/Configurator/Traits/ServerVariablesTrait.php
@@ -22,7 +22,7 @@ trait ServerVariablesTrait
      */
     private array $variables = [];
 
-    public function variable(string $name, string $default, string $description = null, array $enum = null, array $specificationExtensions = []): static
+    public function variable(string $name, string $default, ?string $description = null, ?array $enum = null, array $specificationExtensions = []): static
     {
         $this->variables[$name] = new ServerVariable($default, $description, $enum, $specificationExtensions);