  We re-derive the renormalization group equation for the effective coupling of
the dimension five operator which corresponds to a Majorana mass matrix for the
Standard Model neutrinos. We find a result which differs somewhat from earlier
calculations, leading to modifications in the evolution of leptonic mixing
angles and CP phases. We also present a general method for calculating
beta-functions from counterterms in MS-like renormalization schemes, which
works for tensorial quantities.
