An attachment lock (27) for a prosthetic limb including a housing (28) having an opening (32) for insertion of a prosthetic locking pin (13). A locking member (29) is mounted within the housing (28) and is arranged releasably to secure an inserted locking pin (13). The lock (27) includes means (35) to adjust the position of the locking member (29) relative to the housing (28) along the axis of an inserted locking pin (13).