diff --git a/core/core.services.yml b/core/core.services.yml
index 0319f0e200..c05d67b4fb 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1662,4 +1662,4 @@ services:
       - { name: event_subscriber }
   messenger:
     class: Drupal\Core\Messenger\Messenger
-    arguments: ['@session.flash_bag']
+    arguments: ['@session.flash_bag', '@page_cache_kill_switch']
diff --git a/core/lib/Drupal/Core/Messenger/Messenger.php b/core/lib/Drupal/Core/Messenger/Messenger.php
index e0707304ad..25f3473263 100644
--- a/core/lib/Drupal/Core/Messenger/Messenger.php
+++ b/core/lib/Drupal/Core/Messenger/Messenger.php
@@ -3,6 +3,7 @@
 namespace Drupal\Core\Messenger;
 
 use Drupal\Component\Render\MarkupInterface;
+use Drupal\Core\PageCache\ResponsePolicy\KillSwitch;
 use Drupal\Core\Render\Markup;
 use Symfony\Component\HttpFoundation\Session\Flash\FlashBagInterface;
 
@@ -21,12 +22,22 @@ class Messenger implements MessengerInterface {
   protected $flashBag;
 
   /**
+   * The page cache kill switch.
+   *
+   * @var \Drupal\Core\PageCache\ResponsePolicy\KillSwitch
+   */
+  protected $killSwitch;
+
+  /**
    * Messenger constructor.
    *
    * @param \Symfony\Component\HttpFoundation\Session\Flash\FlashBagInterface $flash_bag
    *   The flash bag.
+   * @param \Drupal\Core\PageCache\ResponsePolicy\KillSwitch $killSwitch
+   *   (optional) The page cache kill switch.
    */
-  public function __construct(FlashBagInterface $flash_bag) {
+  public function __construct(FlashBagInterface $flash_bag, KillSwitch $killSwitch) {
+    $this->killSwitch = $killSwitch;
     $this->flashBag = $flash_bag;
   }
 
@@ -43,6 +54,10 @@ public function addMessage($message, $type = self::TYPE_STATUS, $repeat = FALSE)
     if ($repeat || !in_array($message, $this->flashBag->peek($type))) {
       $this->flashBag->add($type, $message);
     }
+
+    // Mark this page as being uncacheable.
+    $this->killSwitch->trigger();
+
     return $this;
   }