diff --git a/lib/open_project/costs/hooks/work_packages_show_attributes.rb b/lib/open_project/costs/hooks/work_packages_show_attributes.rb
index 01df724939..f858bef030 100644
--- a/lib/open_project/costs/hooks/work_packages_show_attributes.rb
+++ b/lib/open_project/costs/hooks/work_packages_show_attributes.rb
@@ -1,19 +1,22 @@
 module OpenProject::Costs::Hooks
-  class WorkPackagesShowHook < Redmine::Hook::Listener
-    include ActionView::Helpers::TagHelper
+  class WorkPackagesShowHook < Redmine::Hook::ViewListener
+    #include ActionView::Helpers::TagHelper
+    #include ActionView::Helpers::NumberHelper
+    #include ActionView::Helpers::UrlHelper
+    #include ActionView::Helpers::TextHelper
     include ActionView::Context
     include WorkPackagesHelper
 
     def work_packages_show_attributes(context = {})
-      work_package = context[:work_package]
-      project = context[:project]
+      @work_package = context[:work_package]
+      @project = context[:project]
       attributes = context[:attributes]
 
-      return unless project.module_enabled? :costs_module
+      return unless @project.module_enabled? :costs_module
 
       attributes.reject!{ |a| a.attribute == :spent_time }
 
-      attributes << cost_work_package_attributes(work_package)
+      attributes << cost_work_package_attributes(@work_package)
       attributes.flatten!
 
       attributes
@@ -21,6 +24,40 @@ module OpenProject::Costs::Hooks
 
     private
 
+    def cost_entries
+      @cost_entries ||= @work_package.cost_entries.visible(User.current, @work_package.project)
+    end
+
+    def material_costs
+      return @material_costs if @material_costs
+
+      cost_entries_with_rate = cost_entries.select{|c| c.costs_visible_by?(User.current)}
+      @material_costs = cost_entries_with_rate.blank? ? nil : cost_entries_with_rate.collect(&:real_costs).sum
+    end
+
+    def time_entries
+      @time_entries ||= @work_package.time_entries.visible(User.current, @work_package.project)
+    end
+
+    def labor_costs
+      return @labor_costs if @labor_costs
+
+      time_entries_with_rate = time_entries.select{|c| c.costs_visible_by?(User.current)}
+      @labor_costs = time_entries_with_rate.blank? ? nil : time_entries_with_rate.collect(&:real_costs).sum
+    end
+
+    def overall_costs
+      return @overall_costs if @overall_costs
+
+      unless material_costs.nil? && @labor_costs.nil?
+        @overall_costs = 0
+        @overall_costs += material_costs unless material_costs.nil?
+        @overall_costs += labor_costs unless labor_costs.nil?
+      else
+        @overall_costs = nil
+      end
+    end
+
     def cost_work_package_attributes(work_package)
       attributes = []
 
@@ -34,7 +71,7 @@ module OpenProject::Costs::Hooks
 
         attributes << work_package_show_table_row(:spent_hours) do
           # TODO: put inside controller or model
-          summed_hours = @time_entries.sum(&:hours)
+          summed_hours = time_entries.sum(&:hours)
 
           summed_hours > 0 ?
             link_to(l_hours(summed_hours), work_package_time_entries_path(work_package)) :
@@ -43,16 +80,16 @@ module OpenProject::Costs::Hooks
 
       end
       attributes << work_package_show_table_row(:overall_costs) do
-        @overall_costs.nil? ?
+        overall_costs.nil? ?
           empty_element_tag :
-          number_to_currency(@overall_costs)
+          number_to_currency(overall_costs)
       end
 
       if User.current.allowed_to?(:view_cost_entries, @project) ||
         User.current.allowed_to?(:view_own_cost_entries, @project)
 
         attributes << work_package_show_table_row(:spent_units) do
-          summarized_cost_entries(@cost_entries, work_package)
+          summarized_cost_entries(cost_entries, work_package)
         end
       end