diff --git a/app/views/gantts/show.html.erb b/app/views/gantts/show.html.erb
index 1c4b40046..0cebd0a65 100644
--- a/app/views/gantts/show.html.erb
+++ b/app/views/gantts/show.html.erb
@@ -201,9 +201,10 @@
       style += "width: #{width}px;"
       style += "height: #{height}px;"
       style += "font-size:0.7em;"
-      style += 'background:#f1f1f1;' if wday > 5
+      clss = "gantt_hdr"
+      clss << " nwday" if @gantt.non_working_week_days.include?(wday)
     %>
-    <%= content_tag(:div, :style => style, :class => "gantt_hdr") do %>
+    <%= content_tag(:div, :style => style, :class => clss) do %>
       <%= day_letter(wday) %>
     <% end %>
     <%
diff --git a/lib/redmine/helpers/gantt.rb b/lib/redmine/helpers/gantt.rb
index 398f8233f..27faf0a96 100644
--- a/lib/redmine/helpers/gantt.rb
+++ b/lib/redmine/helpers/gantt.rb
@@ -21,6 +21,7 @@ module Redmine
     class Gantt
       include ERB::Util
       include Redmine::I18n
+      include Redmine::Utils::DateCalculation
 
       # :nodoc:
       # Some utility methods for the PDF export
diff --git a/public/stylesheets/application.css b/public/stylesheets/application.css
index 3e5ead969..f45d408d7 100644
--- a/public/stylesheets/application.css
+++ b/public/stylesheets/application.css
@@ -879,6 +879,8 @@ a.close-icon:hover {background-image:url('../images/close_hl.png');}
   overflow: hidden;
 }
 
+.gantt_hdr.nwday {background-color:#f1f1f1;}
+
 .gantt_subjects { font-size: 0.8em; }
 .gantt_subjects div { line-height:16px;height:16px;overflow:hidden;white-space:nowrap;text-overflow: ellipsis; }