A space in which every infinite set contains an infinite subset with only a finite number of accumulation points is said to have the finite derived set property. We study this property in the class of spaces in which compact sets are closed -- the KC-spaces -- and apply our results to show that among hereditarily Lindel\"of spaces, minimal KC-spaces are compact. This result generalizes a theorem of \cite{AW} and gives a partial answer to a question of R. Larson.