We performed Adiabatic Scanning Calorimetry (ASC) measurements on two ferroelectric liquid crystals: S-(-)-4-(20-methylbutyloxy)phenyl4-n-octyloxybenzoate and S-(-)-2-methylbutyl 4-n-nonanoyloxybiphenyl-4'-carboxylate. Our experiments showed that no latent heat was present for the smectic-A-smectic-C* (AC*) transition to within the experimental resolution. Therefore the AC* transition in both samples can be classified as a continuous one. By fitting the specific heat data we showed that this phase transition can be described by an extended mean-field model.