Issue #2255 has been updated by Vit Ondruch. For me, internal encoding doesn't matter, since the conversion is pretty easy. But important is that the following example will work properly: C:\>echo puts ARGV[0] > uparam.rb C:\>ruby\bin\ruby.exe uparam.rb ca_zufllige_luouk_§â§Ñ§Ù§Ý§à§Ô§Ñ c?a_zuf¥Æ¡¢llige_¥ÄÛÍu¥ÄÙÐu¥È¹Ì¥Æ¥¹_??????? C:\> ---------------------------------------- http://redmine.ruby-lang.org/issues/show/2255 ---------------------------------------- http://redmine.ruby-lang.org