  Massive, luminous stars reaching the Eddington limit in their interiors
develop very dilute, extended envelopes. This effect is called envelope
inflation. If the progenitors of Type Ib/c supernovae, which are believed to be
Wolf-Rayet (WR) stars, have inflated envelopes then the shock breakout signals
diffuse in them and can extend their rise times significantly. We show that our
inflated, hydrogen-free, WR stellar models with a radius of ~Rsun can have
shock breakout signals longer than ~60 s. The puzzlingly long shock breakout
signal observed in the Type Ib SN 2008D can be explained by an inflated
progenitor envelope, and more such events might argue in favour of existence of
inflated envelopes in general.
