Undiscounted utilitarianism as a criterion of intergeneration justice has been questioned for different reasons: It has been argued (1) that any complete ordering of allocations with an infinite number of generations guaranteeing an optimal allocation must involve discounting, and (2) that undiscounted utilitarianism subjects the present generation to heavy demands and leads to outcomes that do not appeal to our ethical intuitions. In a previous work (Asheim, Buchholz & Tungodden, forthcoming in J. Env. Econ. Man.) we have shown that equal treatment of different generations is not incompatible with the existence of maximal allocations, given that one considers technologies that are productive (in a given sense). In this paper we consider the second argument. We show within three classes of technologies (linear, Ramsey and Dasgupta-Heal-Solow tech-nologies) that undiscounted utilitarianism is so malleable that any efficient and non-decreasing allocation can be the unique optimum given the utilitarian criterion, provided that the utility function is appropriately chosen. Hence, undiscounted utilitarianism allows for optimal allocations and need not lead to unequal distributions imposing a too heavy burden on the present generation.