  In 1981/82, Hickin \& Plotkin and McKenzie both proved that a finite group
has only countably many non-isomorphic subdirect powers if and only if it is
abelian. In this paper, we prove that a finite commutative semigroup has only
countably many non-isomorphic countable subdirect powers if and only if it is
either a finite abelian group or a null semigroup.
