diff --git a/src/Symfony/Component/HttpFoundation/StreamedResponse.php b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
index ea2b73f874ba6..af03835b7f8a6 100644
--- a/src/Symfony/Component/HttpFoundation/StreamedResponse.php
+++ b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
@@ -26,7 +26,7 @@
  */
 class StreamedResponse extends Response
 {
-    protected \Closure $callback;
+    protected ?\Closure $callback = null;
     protected bool $streamed = false;
 
     private bool $headersSent = false;