Morris et al. pointed out that the free volume concept is inadequate to reconcile the experimentally observed dynamic behavior that Aroclor 1248 shows in Aroclor/polystyrene or Aroclor/1,4-polybutadiene dilute solution. The present paper shows that if the concentration dependence of the thermal expansivity of the free volume is taken into account, Fujita's free volume theory can be made consistent with the main features of these data, though not perfectly.