diff --git a/HttpServer/Http/Response.php b/HttpServer/Http/Response.php
index 5426915a..2e07f55c 100644
--- a/HttpServer/Http/Response.php
+++ b/HttpServer/Http/Response.php
@@ -101,15 +101,20 @@ class Response extends Application
 	 */
 	public function addHeader($key, $value)
 	{
-		if (
-			!($this->response instanceof SResponse) ||
-			!($this->response instanceof S2Response)
-		) {
+		if ($this->isClient()) {
 			return;
 		}
 		$this->response->header($key, $value);
 	}
 
+	/**
+	 * @return bool
+	 */
+	private function isClient()
+	{
+		return !($this->response instanceof SResponse) && !($this->response instanceof S2Response);
+	}
+
 	/**
 	 * @param string $context
 	 * @param int $statusCode