invalid multibyte escape when installing in ruby 1.9.3

[RajeswariMK]

I added metrical in my gemfile gem 'metrical', :require => false bundle install bundle exec metrical gave the following error

.rvm/gems/ruby-1.9.3-p374/gems/ruby_parser-2.3.1/lib/ruby_parser_extras.rb:612:in `initialize': invalid multibyte escape: /[\x80-\xff]/ (RegexpError)

rails version : 3.2.9 ruby version : 1.9.3

What should i change to run metrical successfully.?