A turbine for a turbo-machine is proposed in which, at a gas inlet for a turbine wheel, vanes extend from a nozzle ring though slots in a shroud. The vanes are formed with a leading portion which is arranged to contact a leading portion of a corresponding slot, and a trailing portion which is shaped, when the leading portion of the vane and slot are together, to be spaced from a corresponding trailing portion of the slot with a substantially constant spacing at room temperature. The contact may be a point contact, e.g. close to the leading edge of the vane. Alternatively, the vane may include a leading surface portion which conforms closely with the shape of a corresponding leading surface portion of one of the slots.