diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index fb09d62c00..4ab97aaf90 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -1237,7 +1237,7 @@ class Response
      */
     protected function ensureIEOverSSLCompatibility(Request $request): void
     {
-        if (false !== stripos($this->headers->get('Content-Disposition'), 'attachment') && 1 == preg_match('/MSIE (.*?);/i', $request->server->get('HTTP_USER_AGENT'), $match) && true === $request->isSecure()) {
+        if (false !== stripos($this->headers->get('Content-Disposition') ?? '', 'attachment') && 1 == preg_match('/MSIE (.*?);/i', $request->server->get('HTTP_USER_AGENT') ?? '', $match) && true === $request->isSecure()) {
             if ((int) preg_replace('/(MSIE )(.*?);/', '$2', $match[0]) < 9) {
                 $this->headers->remove('Cache-Control');
             }