  In the paper ``Density perturbations in the ekpyrotic scenario'', it is
argued that the expected spectrum of primordial perturbations should be scale
invariant in this scenario. Here we show that, contrary to what is claimed in
that paper, the expected spectrum depends on an arbitrary choice of matching
variable. As no underlying (microphysical) principle exists at the present time
that could lift the arbitrariness, we conclude that the ekpyrotic scenario is
not yet a predictive model.
