  The singularity in Hawking and Turok's model (hep-th/9802030) of open
inflation has some appealing properties. We suggest that this singularity
should be regularized with matter. The singular instanton can then be obtained
as the limit of a family of ``no-boundary'' solutions where both the geometry
and the scalar field are regular. Using this procedure, the contribution of the
singularity to the Euclidean action is just 1/3 of the Gibbons-Hawking boundary
term. Unrelated to this question, we also point out that gravitational
backreaction improves the behaviour of scalar perturbations near the
singularity. As a result, the problem of quantizing scalar perturbations and
gravity waves seems to be very well posed.
