I've been trying to install Nokogiri on Mac OS 10.9.3 and whatever I try, the install fails in the end with the following error message: $ sudo gem install nokogiri -- --with-xml2-include=/usr/local/Cellar/libxml2/2.9.1/include/libxml2 --with-xml2-lib=/usr/local/Cellar/libxml2/2.9.1/lib --with-xslt-dir=/usr/local/Cellar/libxslt/1.1.28 --with-iconv-include=/usr/local/Cellar/libiconv/1.14/include --