Energy levels in InP/Ga0.47In0.53As quantum wells are calculated after reformulating the energy-dependent effective mass to be used for taking into account the energy-band nonparabolicity of both constituents. The required value of the ratio of the conduction-band and valence-band discontinuities is found to be close to 2/3, in agreement with the value found by other methods. The value of the nonparabolicity factor is also found to be the same as that used in earlier transport studies.