=> Bootstrap dependency digest>=20010302: found digest-20121220
=> Checksum SHA1 OK for slock-1.0.tar.gz
=> Checksum RMD160 OK for slock-1.0.tar.gz
===> Installing dependencies for slock-1.0
=> Build dependency x11-links>=0.72: found x11-links-0.74
===> Overriding tools for slock-1.0
===> Extracting for slock-1.0
===> Patching for slock-1.0
===> Creating toolchain wrappers for slock-1.0
ERROR: zlib>=1.1.4nb1 is not installed; can't buildlink files.
*** Error code 1

Stop.
bmake: stopped in /usr/pkgsrc/x11/slock
*** Error code 1

Stop.
bmake: stopped in /usr/pkgsrc/x11/slock