diff --git a/app/controllers/admin_controller.rb b/app/controllers/admin_controller.rb
index 7302965..9d311a3 100755
--- a/app/controllers/admin_controller.rb
+++ b/app/controllers/admin_controller.rb
@@ -9,7 +9,7 @@ class AdminController < ApplicationController
     if params[:field].nil?
       fields = "*"
     else
-      fields = params[:field].map {|k,v| k }.join(",")
+      fields = custom_fields.join(",")
     end
 
     if params[:ip]
@@ -61,6 +61,11 @@ class AdminController < ApplicationController
 
   private
 
+  def custom_fields
+    params.require(:field).keys
+  end
+  helper_method :custom_fields
+
   def admin_param
     params[:admin_id] != '1'
   end
diff --git a/app/views/layouts/admin/_analytics.html.erb b/app/views/layouts/admin/_analytics.html.erb
index ba0c436..e088076 100644
--- a/app/views/layouts/admin/_analytics.html.erb
+++ b/app/views/layouts/admin/_analytics.html.erb
@@ -10,7 +10,7 @@
       <thead>
         <tr>
           <%
-          count = (params[:field] ? (params[:field].count+1) : 6)
+          count = (params[:field] ? (custom_fields.count+1) : 6)
           count.times do %>
           <th>&nbsp;</th>
           <% end %>