Assume we could someday create artificial creatures with intelligence comparable to our own. Could it be ethical use them as unpaid labor? There is very little philosophical literature on this topic, but the consensus so far has been that such robot servitude would merely be a new form of slavery. Against this consensus I defend the permissibility of robot servitude, and in particular the controversial case of designing robots so that they want to serve (more or less particular) human ends. A typical objection to this case draws an analogy to the genetic engineering of humans: if designing eager robot servants is permissible, it should also be permissible to design eager human servants. Few ethical views can easily explain even the wrongness of such human engineering, however, and those few explanations that are available break the analogy with engineering robots. The case turns out to be illustrative of profound problems in the field of population ethics.