  We include the new, five-loop, O(alpha_s^4) correction into the QCD sum rule
used for the s-quark mass determination. The pseudoscalar Borel sum rule is
taken as a study case. The OPE for the correlation function with N^4LO,
O(alpha_s^4) accuracy in the perturbative part, and with dimension <= 6
operators reveals a good convergence. We observe a significant improvement of
stability of the sum rule with respect to the variation of the renormalization
scale after including the O(alpha_s^4) correction. We obtain the interval m_s(2
GeV)=105 \pm 6 \pm 7 MeV, which exhibits about 2 MeV increase of the central
value, if the O(alpha_s^4) terms are removed.
