  We have produced detailed evolutionary models of the binary EK Cep using the
CESAM stellar evolution code (Morel 1997). A $\chi^2$-minimisation was
performed to derive the most reliable set of modelling parameters. We have
found that an evolutionary age of about 26.8 Myrs fits both components in the
same isochrone. The positions of EK Cep A and B in the HR diagram are
consistent (within the observational uncertainties) with our results.
  Our revised calibration shows clearly that EK Cep is in the beginning of the
main sequence, while EK Cep B is indeed a PMS star. Such a combination allows
for a precise age determination of the binary, and provides a strict test of
the modelling. In particular we have found that the definition of the time step
in calculating the PMS evolution is crucial to reproduce the observations. A
discussion of the optimal time step for calculating PMS evolution is presented.
  The fitting to the radii of both components is a more difficult task;
although we managed to do it for EK Cep B, EK Cep A has a lower radius than our
best models.
  We further studied the effect of the inclusion of a moderate convective
overshooting; the calibration of the binary is not significantly altered, but
the effect of the inclusion of overshooting can be dramatic in the approach to
the main sequence of stars with masses high enough to burn hydrogen through the
CNO cycle on the main sequence.
