  We consider a model with arbitrary numbers of Majorana fermion fields and
real scalar fields $\varphi_a$, general Yukawa couplings and a $\mathbb{Z}_4$
symmetry that forbids linear and trilinear terms in the scalar potential.
Moreover, fermions become massive only after spontaneous symmetry breaking of
the $\mathbb{Z}_4$ symmetry by vacuum expectation values (VEVs) of the
$\varphi_a$. Introducing the shifted fields $h_a$ whose VEVs vanish,
$\overline{\mbox{MS}}$ renormalization of the parameters of the unbroken theory
suffices to make the theory finite. However, in this way, beyond tree level it
is necessary to perform finite shifts of the tree-level VEVs, induced by the
finite parts of the tadpole diagrams, in order to ensure vanishing one-point
functions of the $h_a$. Moreover, adapting the renormalization scheme to a
situation with many scalars and VEVs, we consider the physical fermion and
scalar masses as derived quantities, $\textit{i.e.}$ as functions of the
coupling constants and VEVs. Consequently, the masses have to be computed order
by order in a perturbative expansion. In this scheme we compute the
selfenergies of fermions and bosons and show how to obtain the respective
one-loop contributions to the tree-level masses. Furthermore, we discuss the
modification of our results in the case of Dirac fermions and investigate, by
way of an example, the effects of a flavour symmetry group.
