diff --git a/src/core/FastCGI/HttpResponse.php b/src/core/FastCGI/HttpResponse.php
index db4fd26..8765c3b 100644
--- a/src/core/FastCGI/HttpResponse.php
+++ b/src/core/FastCGI/HttpResponse.php
@@ -33,7 +33,7 @@ class HttpResponse extends Response
     public function __construct(array $records = [])
     {
         parent::__construct($records);
-        $body = (string) $this->getBody();
+        $body = $this->getBody();
         if (strlen($body) === 0) {
             return;
         }
diff --git a/src/core/FastCGI/Message.php b/src/core/FastCGI/Message.php
index 745f03c..6d299c0 100644
--- a/src/core/FastCGI/Message.php
+++ b/src/core/FastCGI/Message.php
@@ -58,7 +58,7 @@ public function getBody(): string
         return $this->body;
     }
 
-    public function withBody($body): self
+    public function withBody(string|\Stringable $body): self
     {
         $this->body = (string) $body;
         return $this;