  We address the problem of potential non-universality of the leading 1/Q power
corrections to jet shapes emerging from the non-inclusive character of these
observables. We consider the thrust distribution as an example and analyse the
non-inclusive contributions which emerge at the two-loop level. Although
formally subleading in $\as$, they modify the existing na{\"\i}ve one-loop
result for the expected magnitude of the power term by a factor of order unity.
Such a promotion of a subleading correction into a numerical factor is natural
since the non-perturbative power terms are explicitly proportional to powers of
the QCD scale $\Lambda$ which can be fixed precisely only at the two-loop
level. The ``jet-shape scaling factor'' depends on the observable but remains
perturbatively calculable. Therefore it does not undermine the universal nature
of 1/Q power corrections, which remain expressible in terms of the universal
running coupling and universal soft-gluon emission.
