another one?

[oxigen@dmage ~]$ sudo gem install rails -v 4.2.0
Building native extensions.  This could take a while...
ERROR:  Error installing rails:
	ERROR: Failed to build gem native extension.

    /usr/bin/ruby -r ./siteconf20150307-18473-eplxf0.rb extconf.rb
checking if the C compiler accepts ... yes
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}/lib64
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/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}/lib64
	--enable-cross-build
	--disable-cross-build

extconf failed, exit code 1

Gem files will remain installed in /usr/local/share/gems/gems/nokogiri-1.6.6.2 for inspection.
Results logged to /usr/local/lib64/gems/ruby/nokogiri-1.6.6.2/gem_make.out