<p>Completeness says that, for every pair of prospects, at least one of the prospects is at least as preferred as the other. I present a new money-pump argument that Completeness is a requirement of rationality. In comparison with earlier money-pump arguments for Completeness, this argument relies on a unidimensional form of stochastic dominance and the behavioural assumption that agents pick in a probabilistic manner when no option is optimal. Moreover, unlike some of the previous arguments, the new argument is based on a forcing money pump, that is, an exploitation scheme where the agent is rationally required at each step to go along with the scheme.</p>