Hiki Error

Accept-Charset encoding error (CGI::InvalidEncoding)
/usr/local/lib/ruby/2.1.0/cgi/core.rb:676:in `block (2 levels) in initialize_query'
/usr/local/lib/ruby/2.1.0/cgi/core.rb:671:in `each'
/usr/local/lib/ruby/2.1.0/cgi/core.rb:671:in `block in initialize_query'
/usr/local/lib/ruby/2.1.0/cgi/core.rb:670:in `each'
/usr/local/lib/ruby/2.1.0/cgi/core.rb:670:in `initialize_query'
/usr/local/lib/ruby/2.1.0/cgi/core.rb:828:in `initialize'
/home/nagato/public_html/hiki/hiki/request.rb:15:in `new'
/home/nagato/public_html/hiki/hiki/request.rb:15:in `initialize'
/home/nagato/public_html/hiki.cgi:25:in `new'
/home/nagato/public_html/hiki.cgi:25:in `<main>'