diff --git a/lib/time_difference.rb b/lib/time_difference.rb
index 589e202..f039177 100644
--- a/lib/time_difference.rb
+++ b/lib/time_difference.rb
@@ -3,6 +3,7 @@
 
 class TimeDifference
 
+  attr_reader :time_diff
   private_class_method :new
 
   TIME_COMPONENTS = [:years, :months, :weeks, :days, :hours, :minutes, :seconds]
@@ -78,6 +79,10 @@ def humanize
       return [diff_parts.join(', '), last_part].join(' and ')
     end
   end
+  
+  def <=>(other)
+    @time_diff <=> other.time_diff   
+  end
 
   private