gem install json -v '1.8.1' Building native extensions.  This could take a while... ERROR:  Error installing json:   ERROR: Failed to build gem native extension.     /usr/local/var/rbenv/versions/2.0.0-p247/bin/ruby extconf.rb creating Makefile make "DESTDIR=" compiling generator.c In file included from /usr/local/var/rbenv/versions/2.0.0-p247/include/ruby-2.0.0/ruby.h:33,                  from ../fbuffer/fbuffer.h:5,                  from generator.c:1: /usr/local/var/rbenv/versions/2.0.0-p247/include/ruby-2.0.0/ruby/ruby.h:51:21: error: string.h: No such file or directory /usr/local/var/rbenv/versions/2.0.0-p247/include/ruby-2.0.0/ruby/ruby.h:61:21: error: stdint.h: No such file or directory /usr/local/var/rbenv/versions/2.0.0-p247/include/ruby-2.0.0/ruby/ruby.h:64:23: error: inttypes.h: No such file or directory /usr/local/var/rbenv/versions/2.0.0-p247/include/ruby-2.0.0/ruby/ruby.h:68:19: error: stdio.h: No such file or directory

xcode-select --install

brew install apple-gcc42

brew update