The sterile neutrino is a viable dark matter candidate that can be produced in the early Universe with a highly non-thermal spectrum of primordial velocities, and would thus have an effect on the abundance of dwarf galaxies. We use sterile neutrino power spectra as an input for semi-analytic models of galaxy formation in order to predict the number of luminous satellite galaxies in a Milky Way-like halo. By assuming that the mass of the Milky Way halo must be no more than 2 × 10¹²M (the adopted upper bound based on current astronomical observations) we are able to constrain the value of L₆ for Ms ≤ 5 keV. We also show that the range of L₆ that is in best agreement with the 3.5 keV line (if produced by decays of 7 keV sterile neutrino) requires that the Milky Way halo has a mass no smaller than 1.2 × 10¹²M.