Many of us share a strong intuitive sense that acts or policies that gravely threaten future people's well-being violate the requirements of justice. This intuition has proven problematic for theories that found justice on reciprocity because future people are viewed as powerless to reciprocate our actions towards them. The non-reciprocity problem appears to deliver a decisive blow to reciprocity-based theories of justice. I wish to dispute this view. I point to two well-known facts about human existence – generations overlap continuously and the old depend upon the young – to show that future generations are not asymmetrically vulnerable to our actions, and therefore that justice as reciprocity is not vulnerable to the non-reciprocity problem.