  The QCD corrections to the moments of the invariant mass distribution in the
semileptonic $\tau$ decays are considered. The effect of the renormalization
scheme dependence on the fitted values of alpha_s(m^2_tau) and the condensates
is discussed, using a simplified approach where the nonperturbative
contributions are approximated by the dimension six condensates. The fits in
the vector and the axial-vector channel are investigated in the next-to-leading
and the next-to-next-to-leading order. The next-to-next-to-leading order
results are found to be relatively stable with respect to change of the
renormalization scheme. A change from the MS-bar scheme to the minimal
sensitivity scheme results in the reduction of the extracted value of
alpha_s(m^2_tau) by 0.01.
