diff --git a/actionpack/lib/action_dispatch/testing/test_request.rb b/actionpack/lib/action_dispatch/testing/test_request.rb
index abc2e9afcc839e4e33c7676884e026ad506eeae2..cf440a1fade79d96559bb50660582151f8653ad2 100644
--- a/actionpack/lib/action_dispatch/testing/test_request.rb
+++ b/actionpack/lib/action_dispatch/testing/test_request.rb
@@ -13,6 +13,7 @@ def initialize(env = {})
       env = Rails.application.env_config.merge(env) if defined?(Rails.application)
       super(DEFAULT_ENV.merge(env))
 
+      @cookies = nil
       self.host        = 'test.host'
       self.remote_addr = '0.0.0.0'
       self.user_agent  = 'Rails Testing'