diff --git a/README.rdoc b/README.rdoc
index 1958f62..f5e346e 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -119,11 +119,14 @@ It is strongly recommended to enable caching. You can see the three paramters wh
     <% if request.post? %>
       <p><%= valid_captcha?(params[:captcha]) ? 'valid' : 'invalid' %> captcha</p>
     <% end %>
-    <p><%= captcha_tag %></p>
+    <p><%= captcha_tag( url , {}) %> </p>
     <p><%= text_field_tag :captcha %></p>
     <p><%= submit_tag 'Validate' %></p>
   <% end %>
 
+== captcha_tag裡的url 要將從被引用的專案使用
+原因: 否則 environment/production.rb 設定 config.action_controller.asset_host 會讓 captcha_tag 帶入asset_host 而無法正常顯示
+
 == Example app
 You find an example app under: http://github.com/phatworx/easy_captcha_example
 
diff --git a/lib/easy_captcha/view_helpers.rb b/lib/easy_captcha/view_helpers.rb
index 1820eee..9f0fe1e 100644
--- a/lib/easy_captcha/view_helpers.rb
+++ b/lib/easy_captcha/view_helpers.rb
@@ -2,10 +2,10 @@ module EasyCaptcha
   # helper class for ActionView
   module ViewHelpers
     # generate an image_tag for captcha image
-    def captcha_tag(*args)
+    def captcha_tag(captcha_image_path = captcha_path(:i => Time.now.to_i), custom_options = {}) 
       options = { :alt => 'captcha', :width => EasyCaptcha.image_width, :height => EasyCaptcha.image_height }
-      options.merge! args.extract_options!
-      image_tag(captcha_path(:i => Time.now.to_i), options)
+      options.merge! custom_options
+      image_tag(captcha_image_path , options)
     end
   end
 end