Trouble installing json gem on mountain lion

I tried running bundle install and it stopped on the json gem. So I tried running running sudo gem install json 1.7.3 which is the version that it crashed on it it gave the following: ``` unknown109addaae0a6:introhive Jody$ sudo gem install json Building native extensions. This could take a while... ERROR: Error installing json: ERROR: Failed to build gem native extension. /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/json-1.7.3 for inspection. Results logged to /Library/Ruby/Gems/1.8/gems/json-1.7.3/ext/json/ext/parser/gem_make.out ``` Then if I look at the gem_make.out file it looks like this: ``` /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h ``` I've tried making sure command line tools were installed, but I'm at a bit of a loss on how to get by this one. Any help would be appreciated. Thanks