An annulus filler assembly for a rotor of a turbomachine, the assembly comprising: an annulus lid (56) having a radially outwardly facing surface (58) for forming an inner wall of a flow annulus of the rotor and a radially inwardly facing surface; and a frame for supporting the annulus lid (40), the frame being mountable to a disc of the rotor such that the annulus lid (56) is spaced away from the disc, wherein the frame (40) comprises a connection portion (46) which, in use, passes through an aperture (60) in the annulus lid (56) from the radially inwardly facing surface towards the radially outwardly facing surface (58) such that at least a portion of the connection portion (46) is visible from the radially outwardly facing surface (58); the assembly further comprising a locking element (68) which locks the connection portion (46) to the annulus lid (56) via the visible portion of the connection portion (46).