FabioLolix [1] filed a deletion request for libxs [2]: The pkgbuild provide and conflicts zeromq but is an unmaintained 10 years old fork of zeromq, while the source can be downloaded from Debian it no longer build (dropped from Debian too), website and github organization no longer exist (https://github.com/crossroads- io/libxs), Debian changelog indicate June 2012 for v1.2.0 update, last known version [1] https://aur.archlinux.org/account/FabioLolix/ [2] https://aur.archlinux.org/pkgbase/libxs/