diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index e012fa617e..cf306e9a9c 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -473,7 +473,7 @@ module ActionController
 
         self.cookies.update @request.cookies
         @request.env['HTTP_COOKIE'] = cookies.to_header
-        @request.env['action_dispatch.cookies'] = nil
+        @request.delete_header 'action_dispatch.cookies'
 
         @request          = TestRequest.new scrub_env!(@request.env), @request.session
         @response         = build_response @response_klass
diff --git a/actionpack/lib/action_dispatch/middleware/cookies.rb b/actionpack/lib/action_dispatch/middleware/cookies.rb
index cf4f654ed6..e4c5b0bd29 100644
--- a/actionpack/lib/action_dispatch/middleware/cookies.rb
+++ b/actionpack/lib/action_dispatch/middleware/cookies.rb
@@ -8,48 +8,50 @@ require 'active_support/json'
 module ActionDispatch
   class Request < Rack::Request
     def cookie_jar
-      env['action_dispatch.cookies'.freeze] ||= Cookies::CookieJar.build(self, cookies)
+      get_header('action_dispatch.cookies'.freeze) do |k|
+        self.cookie_jar = Cookies::CookieJar.build(self, cookies)
+      end
     end
 
     # :stopdoc:
     def have_cookie_jar?
-      env.key? 'action_dispatch.cookies'.freeze
+      has_header? 'action_dispatch.cookies'.freeze
     end
 
     def cookie_jar=(jar)
-      env['action_dispatch.cookies'.freeze] = jar
+      set_header 'action_dispatch.cookies'.freeze, jar
     end
 
     def key_generator
-      env[Cookies::GENERATOR_KEY]
+      get_header Cookies::GENERATOR_KEY
     end
 
     def signed_cookie_salt
-      env[Cookies::SIGNED_COOKIE_SALT]
+      get_header Cookies::SIGNED_COOKIE_SALT
     end
 
     def encrypted_cookie_salt
-      env[Cookies::ENCRYPTED_COOKIE_SALT]
+      get_header Cookies::ENCRYPTED_COOKIE_SALT
     end
 
     def encrypted_signed_cookie_salt
-      env[Cookies::ENCRYPTED_SIGNED_COOKIE_SALT]
+      get_header Cookies::ENCRYPTED_SIGNED_COOKIE_SALT
     end
 
     def secret_token
-      env[Cookies::SECRET_TOKEN]
+      get_header Cookies::SECRET_TOKEN
     end
 
     def secret_key_base
-      env[Cookies::SECRET_KEY_BASE]
+      get_header Cookies::SECRET_KEY_BASE
     end
 
     def cookies_serializer
-      env[Cookies::COOKIES_SERIALIZER]
+      get_header Cookies::COOKIES_SERIALIZER
     end
 
     def cookies_digest
-      env[Cookies::COOKIES_DIGEST]
+      get_header Cookies::COOKIES_DIGEST
     end
     # :startdoc:
   end