  We calculate the S parameter of the standard model at one loop of fermions,
using three different regularizations (dimensional, Pauli-Villars and lattice)
and find an extra contribution to the S parameter besides the standard one for
each case. This shows that the extra contribution recently reported for the
lattice regularization is {\it not} necessarily tied to the non-decoupling
effect of fermion doublers. We argue that the extra contribution should be
subtracted in the renormalizable perturbative expansion.
