nokogiri build

gistfile1.txt

Building native extensions.  This could take a while...
ERROR:  Error installing nokogiri:
	ERROR: Failed to build gem native extension.

    /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -r ./siteconf20150911-86955-1dr4u7z.rb extconf.rb
checking if the C compiler accepts ... yes
checking if the C compiler accepts -Wno-error=unused-command-line-argument-hard-error-in-future... no
Building nokogiri using packaged libraries.
checking for gzdopen() in -lz... no
zlib is missing; necessary for building libxml2
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
	--help
	--clean
	--use-system-libraries
	--enable-static
	--disable-static
	--with-zlib-dir
	--without-zlib-dir
	--with-zlib-include
	--without-zlib-include=${zlib-dir}/include
	--with-zlib-lib
	--without-zlib-lib=${zlib-dir}/lib
	--enable-cross-build
	--disable-cross-build

extconf failed, exit code 1

Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/nokogiri-1.6.6.2/gem_make.out