--- a/lib/chronos/datetime/gregorian.rb
+++ b/lib/chronos/datetime/gregorian.rb
@@ -257,8 +257,8 @@ module Chronos
                        # change to another timezone, also gives the opportunity to change language
                        def change_zone(timezone=nil, language=nil)
                                timezone ||= @timezone
-                               timezone = Zone[timezone] unless timezone.kind_of?(Zone)
-                               Datetime.new(@day_number, @ps_number, timezone, language)
+                               timezone = Chronos::Zone[timezone] unless timezone.kind_of?(Chronos::Zone)
+                               self.class.new(@day_number, @ps_number, timezone, language)
                        end
        
                        # this method calculates @day_of_year and @year from @day_number - only used internally