Zlib has a potential buffer overflow in its gzprintf() function, that, though difficult to take advantage of, should be taken care of. Do so by applying this patch: patch -Np1 -i ../zlib-&zlib-patch-version;.patch Now prepare Zlib for compilation: ./configure --prefix=/usr --shared Note: Zlib is known to build it's shared library incorrectly if a CFLAGS is specified in the environment. If you are using your own CFLAGS variables, ensure you add the -fPIC directive during this stage, and remove it after. Compile the package: make Install the shared libraries: make install Now also build and install the non-shared libraries: make clean ./configure --prefix=/usr make make test make install The shared Zlib library should be installed in the /lib directory. That way, in the event that you must boot without the /usr directory, vital system programs will still have access to the library: mv /usr/lib/libz.so.* /lib The /usr/lib/libz.so symlink is linked to a file which no longer exists, because we moved it. Create a symbolic link to the new location of the library: ln -sf ../../lib/libz.so.1 /usr/lib/libz.so Zlib does not install its manual page. Issue the following command to install this documentation: cp zlib.3 /usr/share/man/man3