Sub-mm surveys have revealed galaxies with very large masses of dust at very high redshifts. To create this much dust at early times is a challenge for theories of dust formation. Recently, it has been argued (and counter-argued) that significant amounts of dust can be created in supernovae and, if true, this can explain the high dust masses in the early Universe. I will present the current observational data in favour of dust in SNe and describe its limitations, as well as some tentative new work which suggests that our interpretation of sub-mm galaxies may need reviewing.