a mere data point: (cygwin-64 ruby includes the full 64-bit Fixnum) >> RUBY_VERSION => "2.2.5" >> `uname -om` => "x86_64 Cygwin\n" >> (1<<61).class => Fixnum >> (1<<62).class => Bignum Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe> <http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>