Set default date1904 attribute using platform string

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/axlsx/workbook/workbook.rb b/lib/axlsx/workbook/workbook.rb
index edb02d81..c5fec5f9 100644
--- a/lib/axlsx/workbook/workbook.rb
+++ b/lib/axlsx/workbook/workbook.rb
@@ -89,10 +89,14 @@ require 'axlsx/workbook/worksheet/worksheet.rb'
       @drawings = SimpleTypedList.new Drawing
       @charts = SimpleTypedList.new Chart
       @images = SimpleTypedList.new Pic
-      self.date1904= options[:date1904] unless options[:date1904].nil?
+      self.date1904= options[:date1904].nil? ? is_darwin? : options[:date1904]
       yield self if block_given?      
     end
 
+    def is_darwin?
+      RUBY_PLATFORM.downcase.include?('darwin')
+    end
+
     # Instance level access to the class variable 1904
     # @return [Boolean]
     def date1904() @@date1904; end