A variable nozzle for a turbocharger includes a plurality of vanes rotatably mounted on a nozzle ring and disposed in a nozzle flow path defined between the nozzle ring and an opposite nozzle wall. Either or both of the faces of the nozzle ring and nozzle wall include(s) grooves extending substantially transverse to a general flow direction of the flow through the nozzle, and there are clearances between the ends of the vanes and the adjacent faces. Leakage flow through the clearance between the end of each vane and the adjacent face having the grooves must proceed across the grooves, and thus a labyrinthine flow passage is presented to the leakage flow. The labyrinthine passage has a greater resistance to flow than would be the case without the grooves. Accordingly, leakage flow is reduced, which is beneficial to turbine efficiency.