Physicalism should be characterized in a way that makes it compatible with the possibility that the physical world is infinitely decomposable. Some have proposed solving this problem by replacing a widely accepted No Fundamental Mentality requirement on physicalism with a more general No Low-Level Mentality requirement. The latter states that physicalism could be true if there is a level of decomposition beneath which nothing is mental, whereas physicalism is false otherwise. Brown (Erkenntnis 82:1339-1350, 2017a) argues that this solution does not work. He devises an infinitely decomposable possible world in which physicalism should come out as trueeven thoughthere is mentality all the way down. I propose a solution that circumvents his argument. The key is to specify thesortof mentality that physicalism cannot abide at any level, namely, mentality that does not consist solely in a structural-dynamic arrangement of entities. I also argue that the problem Brown identifies has significant implications for what is at stake in the debate over physicalism's truth or falsity-implications he undersells.