diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index 2da3a6549989c..c14a7bbfdfcb5 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -1236,6 +1236,7 @@ public static function closeOutputBuffers(int $targetLevel, bool $flush): void
         while ($level-- > $targetLevel && ($s = $status[$level]) && (!isset($s['del']) ? !isset($s['flags']) || ($s['flags'] & $flags) === $flags : $s['del'])) {
             if ($flush) {
                 ob_end_flush();
+                flush();
             } else {
                 ob_end_clean();
             }