Foreign character encoding crashes sup

sup crashes when responding to a mail with character encoding set to EUC-KR. exception-log.txt below:

    --- Encoding::CompatibilityError from thread: main
    incompatible character encodings: UTF-8 and EUC-KR
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/lib/sup/modes/edit_message_mode.rb:200:in `join'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/lib/sup/modes/edit_message_mode.rb:200:in `save_message_to_file'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/lib/sup/modes/edit_message_mode.rb:225:in `edit_message'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/lib/sup/mode.rb:59:in `handle_input'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/lib/sup/buffer.rb:273:in `handle_input'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/bin/sup:265:in `<module:Redwood>'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/gems/sup-0.14.0/bin/sup:73:in `<top (required)>'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/bin/sup:23:in `load'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/bin/sup:23:in `<main>'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/bin/ruby_noexec_wrapper:14:in `eval'
    /Users/akojo/.rvm/gems/ruby-1.9.3-p448/bin/ruby_noexec_wrapper:14:in `<main>'