  This paper presents a necessary and sufficient condition on a category with
weak finite limits for its exact completion to be (locally) cartesian closed. A
paper by Carboni and Rosolini already claimed such a characterisation using a
different property on the base category, but we shall show that weak finite
limits are not enough for their proof to go through. We shall also indicate how
to strengthen the hypothesis for that proof to work. It will become clear that,
in the case of ex/lex completions, their characterisation is still valid and it
coincides with the one presented here.
