A cutting block comprises a body having a top surface for guiding a saw blade, and a top plate connected to the body. The top plate can move between a first position in which the top plate is spaced apart from the body and a second position in which the top surface of the top plate is an extension of the top surface of the body. The top plate has first and second resiliently deformable arms extending from it, spaced apart along the top plate, and the body has first and second recesses formed in it extending substantially perpendicularly to the top surface of the body. The first and second arms on the top plate are inserted in the recesses so that the arms and the recesses define the path for movement of the top plate relative to the body between the first and second position.