diff --git a/actionpack/lib/action_controller/session/cookie_store.rb b/actionpack/lib/action_controller/session/cookie_store.rb
index 158c940cc2..ba63f8521f 100644
--- a/actionpack/lib/action_controller/session/cookie_store.rb
+++ b/actionpack/lib/action_controller/session/cookie_store.rb
@@ -93,7 +93,7 @@ module ActionController
         original_value = session_data.dup
 
         env[ENV_SESSION_KEY] = session_data
-        env[ENV_SESSION_OPTIONS_KEY] = @default_options.dup
+        env[ENV_SESSION_OPTIONS_KEY] = @default_options
 
         status, headers, body = @app.call(env)