  We construct a new Hartree-Fock-Bogoliubov (HFB) mass model, labeled HFB-18,
with a generalized Skyrme force. The additional terms that we have introduced
into the force are density-dependent generalizations of the usual $t_1$ and
$t_2$ terms, and are chosen in such a way as to avoid the high-density
ferromagnetic instability of neutron stars that is a general feature of
conventional Skyrme forces, and in particular of the Skyrme forces underlying
all the HFB mass models that we have developed in the past. The remaining
parameters of the model are then fitted to essentially all the available mass
data, an rms deviation $\sigma$ of 0.585 MeV being obtained. The new model thus
gives almost as good a mass fit as our best-fit model HFB-17 ($\sigma$ = 0.581
MeV), and has the advantage of avoiding the ferromagnetic collapse of neutron
stars.
