The unconventional filled skutterudite superconductor, PrPt4Ge12(Tc ~ 7.9 K), was recently discovered, for which zero field muon spin relaxation (ZF-MuSR) experiments reveal that time-reversal symmetry (TRS) breaking occurs below Tc. The origin of the TRS breaking is not clear, it might be due to an unconventional multicomponent order parameter arising from either the spin or orbital degeneracy of the Cooper pairs. In order to study the effect of impurities on the superconducting state, we investigated the chemical substitution series Pr1-xCexPt4Ge12, for which CePt4Ge12 exhibits fluctuating valence behavior and no magnetic order above 0.48 K. In this series, superconductivity persists unusually to high values of x. We propose to study how the TRS-breaking superconductivity of PrPt4Ge12 evolves with Ce substitution by applying for 8-days ZF-MuSR beam time.