Two Ca-Al-rich inclusions from the Allende meteorite have been found to have undergone large mass-fractionation of oxygen isotopes subsequent to incorporation of the nucleosynthetic 16O-anomaly found in other Allende inclusions. The magnitude of the oxygen isotope fractionations is in constant ratio to the magnesium isotope fractionations found in the same inclusions by Wasserburg, Lee and Papanastassiou. The observations support earlier theories of the addition of supernova ejecta into the solar nebula just prior to collapse and condensation.