diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 35c8a40..f7400bc 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -854,6 +854,8 @@ module ApplicationHelper
           'Calendar._FD = 1;' # Monday
         when 7
           'Calendar._FD = 0;' # Sunday
+        when 6
+          'Calendar._FD = 6;' # Saturday
         else
           '' # use language
         end
diff --git a/app/views/settings/_display.rhtml b/app/views/settings/_display.rhtml
index 97cee52..25f65fc 100644
--- a/app/views/settings/_display.rhtml
+++ b/app/views/settings/_display.rhtml
@@ -5,7 +5,7 @@
 
 <p><%= setting_select :default_language, lang_options_for_select(false) %></p>
 
-<p><%= setting_select :start_of_week, [[day_name(1),'1'], [day_name(7),'7']], :blank => :label_language_based %></p>
+<p><%= setting_select :start_of_week, [[day_name(1),'1'], [day_name(6),'6'], [day_name(7),'7']], :blank => :label_language_based %></p>
 
 <p><%= setting_select :date_format, Setting::DATE_FORMATS.collect {|f| [Date.today.strftime(f), f]}, :blank => :label_language_based %></p>
 
diff --git a/lib/redmine/helpers/calendar.rb b/lib/redmine/helpers/calendar.rb
index ec47402..9b3c0e8 100644
--- a/lib/redmine/helpers/calendar.rb
+++ b/lib/redmine/helpers/calendar.rb
@@ -68,6 +68,8 @@ module Redmine
         case Setting.start_of_week.to_i
         when 1
           @first_dow ||= (1 - 1)%7 + 1
+        when 6
+          @first_dow ||= (6 - 1)%7 + 1
         when 7
           @first_dow ||= (7 - 1)%7 + 1
         else
diff --git a/test/unit/lib/redmine/helpers/calendar_test.rb b/test/unit/lib/redmine/helpers/calendar_test.rb
index 8375234..f0ac678 100644
--- a/test/unit/lib/redmine/helpers/calendar_test.rb
+++ b/test/unit/lib/redmine/helpers/calendar_test.rb
@@ -1,5 +1,5 @@
-# redMine - project management software
-# Copyright (C) 2006-2007  Jean-Philippe Lang
+# Redmine - project management software
+# Copyright (C) 2006-2011  Jean-Philippe Lang
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -40,4 +40,24 @@ class CalendarTest < ActiveSupport::TestCase
     c = Redmine::Helpers::Calendar.new(Date.today, :en, :week)
     assert_equal [7, 6], [c.startdt.cwday, c.enddt.cwday]
   end
+  
+  def test_monthly_start_day
+    [1, 6, 7].each do |day|
+      with_settings :start_of_week => day do
+        c = Redmine::Helpers::Calendar.new(Date.today, :en, :month)
+        assert_equal day , c.startdt.cwday
+        assert_equal (day + 5) % 7, c.enddt.cwday
+      end
+    end
+  end
+  
+  def test_weekly_start_day
+    [1, 6, 7].each do |day|
+      with_settings :start_of_week => day do
+        c = Redmine::Helpers::Calendar.new(Date.today, :en, :week)
+        assert_equal day, c.startdt.cwday
+        assert_equal (day + 5) % 7 + 1, c.enddt.cwday
+      end
+    end
+  end
 end