The present invention provides a connector for terminating an optical fiber. The connector comprises a one-piece housing, a ferrule assembly and an insert. The insert has keys formed thereon that are adapted to mate with keyways formed in the housing. The housing has a first opening formed therein that first receives the ferrule assembly and then the insert and a second opening opposite the first opening. The end of the ferrule assembly that holds the end of the optical fiber protrudes through the second opening. The insert has a flange thereon that has two oppositely located flat surfaces and two oppositely located keys. The keys each have a chamfered surface. The keys and the flat surfaces of the flange provide the flange with a substantially rectangular cross-section. The first opening formed in the housing has a substantially square cross-section. When the insert is inserted into the first end of the housing, the substantially square cross-section of the opening aligns with the oppositely located flat surfaces of the flange to thereby cause the keys of the flange to align with the keyways formed in the surfaces of the housing. The chamfered surfaces of the keys deflect the sides of the housing outwardly as the insert is inserted into the housing. The keys of the insert are then received by the keyways formed in the housing to lock the insert into place within the housing.