diff --git a/http-server/Message/Response.php b/http-server/Message/Response.php
index c068ca9b..04a2619d 100644
--- a/http-server/Message/Response.php
+++ b/http-server/Message/Response.php
@@ -99,30 +99,30 @@ class Response implements ResponseInterface, \Server\ResponseInterface
 
 
 	/**
-	 * @param string $value
+	 * @param string|null $value
 	 * @return Response
 	 */
-	public function withAccessControlAllowHeaders(string $value): static
+	public function withAccessControlAllowHeaders(?string $value): static
 	{
 		return $this->withHeader('Access-Control-Allow-Headers', $value);
 	}
 
 
 	/**
-	 * @param string $value
+	 * @param string|null $value
 	 * @return Response
 	 */
-	public function withAccessControlRequestMethod(string $value): static
+	public function withAccessControlRequestMethod(?string $value): static
 	{
 		return $this->withHeader('Access-Control-Request-Method', $value);
 	}
 
 
 	/**
-	 * @param string $value
+	 * @param string|null $value
 	 * @return Response
 	 */
-	public function withAccessControlAllowOrigin(string $value): static
+	public function withAccessControlAllowOrigin(?string $value): static
 	{
 		return $this->withHeader('Access-Control-Allow-Origin', $value);
 	}
diff --git a/http-server/ResponseInterface.php b/http-server/ResponseInterface.php
index d7589b3d..a0ccef64 100644
--- a/http-server/ResponseInterface.php
+++ b/http-server/ResponseInterface.php
@@ -69,24 +69,24 @@ interface ResponseInterface extends \Psr\Http\Message\ResponseInterface
 
 
 	/**
-	 * @param string $value
+	 * @param ?string $value
 	 * @return ResponseInterface
 	 */
-	public function withAccessControlAllowOrigin(string $value): ResponseInterface;
+	public function withAccessControlAllowOrigin(?string $value): ResponseInterface;
 
 
 	/**
-	 * @param string $value
+	 * @param ?string $value
 	 * @return ResponseInterface
 	 */
-	public function withAccessControlRequestMethod(string $value): ResponseInterface;
+	public function withAccessControlRequestMethod(?string $value): ResponseInterface;
 
 
 	/**
-	 * @param string $value
+	 * @param ?string $value
 	 * @return ResponseInterface
 	 */
-	public function withAccessControlAllowHeaders(string $value): ResponseInterface;
+	public function withAccessControlAllowHeaders(?string $value): ResponseInterface;