diff --git a/UPGRADE-4.3.md b/UPGRADE-4.3.md
index 2e6c64b2b9..4eb383d467 100644
--- a/UPGRADE-4.3.md
+++ b/UPGRADE-4.3.md
@@ -4,6 +4,7 @@ UPGRADE FROM 4.2 to 4.3
 BrowserKit
 ----------
 
+ * Marked `Response` final.
  * Deprecated `Response::buildHeader()`
  * Deprecated `Response::getStatus()`, use `Response::getStatusCode()` instead
 
diff --git a/UPGRADE-5.0.md b/UPGRADE-5.0.md
index f1acd19eff..f446a7c15a 100644
--- a/UPGRADE-5.0.md
+++ b/UPGRADE-5.0.md
@@ -4,6 +4,7 @@ UPGRADE FROM 4.x to 5.0
 BrowserKit
 ----------
 
+ * Removed the possibility to extend `Response` by making it final.
  * Removed `Response::buildHeader()`
  * Removed `Response::getStatus()`, use `Response::getStatusCode()` instead
  * The `Client::submit()` method has a new `$serverParameters` argument.
diff --git a/src/Symfony/Component/BrowserKit/CHANGELOG.md b/src/Symfony/Component/BrowserKit/CHANGELOG.md
index 37a724261a..5ff92bb024 100644
--- a/src/Symfony/Component/BrowserKit/CHANGELOG.md
+++ b/src/Symfony/Component/BrowserKit/CHANGELOG.md
@@ -4,6 +4,7 @@ CHANGELOG
 4.3.0
 -----
 
+ * Marked `Response` final.
  * Deprecated `Response::buildHeader()`
  * Deprecated `Response::getStatus()`, use `Response::getStatusCode()` instead
 
diff --git a/src/Symfony/Component/BrowserKit/Response.php b/src/Symfony/Component/BrowserKit/Response.php
index 9045da5673..845be10b68 100644
--- a/src/Symfony/Component/BrowserKit/Response.php
+++ b/src/Symfony/Component/BrowserKit/Response.php
@@ -13,11 +13,16 @@ namespace Symfony\Component\BrowserKit;
 
 /**
  * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @final since Symfony 4.3
  */
 class Response
 {
+    /** @internal */
     protected $content;
+    /** @internal */
     protected $status;
+    /** @internal */
     protected $headers;
 
     /**