diff --git a/src/App/Action/AvatarAction.php b/src/App/Action/AvatarAction.php
index fe5366b..ed6b298 100644
--- a/src/App/Action/AvatarAction.php
+++ b/src/App/Action/AvatarAction.php
@@ -26,8 +26,9 @@ class AvatarAction implements ServerMiddlewareInterface
         }
 
         $avatarData = $this->avatarService->getAvatarData($signum);
-        return new TextResponse($avatarData, 200, [
+        return (new TextResponse($avatarData, 200, [
             'content-type' => 'image/png',
-        ]);
+        ]))->withHeader('Expires', '0')
+            ->withHeader('Cache-Control', 'must-revalidate');
     }
 }