  In a series of recent papers, including arXiv:1210.1183, it was claimed that
large-scale magnetic fields generated during inflation in a spatially open
universe could remain astrophysically significant at the present time since
they experienced superadiabatic amplification specific to an open universe. We
reexamine this assertion and show that, on the contrary, large-scale magnetic
fields in a realistic open universe decay in much the same manner as they would
in a spatially flat universe. Consequently, their amplitude today is extremely
small (B0 < 10^{-59} G) and is unlikely to be of astrophysical significance.
