A turbine blade 29 for a gas turbine engine 10 having an axis 20, the turbine blade 29 comprising: an aerofoil 30 including a high pressure surface 36, a low pressure surface 34, a root portion 38 and a tip surface 40 extending transverse from the high and low pressure surfaces 36 and 34, the high and low pressure surfaces 36 and 34 curve from the root portion 38 to the tip surface 40 in a direction that is substantially tangential to the axis 20 of the engine 10; and an air leakage restricting member 32 on the tip surface 40, the air leakage restricting member 32 being configured to substantially prevent leakage of air over the tip surface 40.