diff --git a/lib/rubykassa.rb b/lib/rubykassa.rb
index c789bba..276df9a 100644
--- a/lib/rubykassa.rb
+++ b/lib/rubykassa.rb
@@ -12,7 +12,7 @@ def configure &block
     Rubykassa::Client.configure &block
   end
 
-  %w(login first_password second_password mode http_method xml_http_method success_callback fail_callback result_callback).map do |name|
+  Rubykassa::Configuration::ATTRIBUTES.map do |name|
     define_method name do
       Rubykassa::Client.configuration.send(name)
     end
diff --git a/lib/rubykassa/configuration.rb b/lib/rubykassa/configuration.rb
index 0e7be96..290499a 100644
--- a/lib/rubykassa/configuration.rb
+++ b/lib/rubykassa/configuration.rb
@@ -1,10 +1,12 @@
 # -*- encoding : utf-8 -*-
 module Rubykassa
   class Configuration
-    attr_accessor :login, :first_password, :second_password, :mode, :http_method, :xml_http_method
-    attr_accessor :success_callback
-    attr_accessor :fail_callback
-    attr_accessor :result_callback
+    ATTRIBUTES = [
+      :login, :first_password, :second_password, :mode, :http_method, :xml_http_method,
+      :success_callback, :fail_callback, :result_callback
+    ]
+
+    attr_accessor *ATTRIBUTES
 
     def initialize
       self.login = "your_login"