An aerofoil for a compressor comprising a suction surface and a pressure surface with a thickness distribution defined therebetween, the aerofoil further comprising a first local maximum in the thickness distribution and a second local maximum in the thickness distribution, the second local maximum being downstream of the first local maximum and the second local maxima being formed by a first region of concave curvature in the suction surface between the first and second local maxima, wherein the second local maximum is disposed such that in use a boundary layer upstream of the second local maximum on the suction surface is thinned by the second local maximum, and in addition the boundary layer may be sufficiently thinned so that an interaction of an upstream flow feature with the thinned boundary layer is capable of generating a turbulent spot with a calmed region downstream of the turbulent spot.