An electrical connector includes a shell having a cavity configured to receive a complementary connector. The shell has a front end and a rear end and a circumferential channel in the cavity. The channel has an undercut defined by a seal retention flange extending circumferentially around the channel. A seal retainer is received in the cavity at the front end. The seal retainer has a front edge and a rear edge received in the channel. The rear edge of the seal retainer has an undercut defined by a seal retention flange. The seal retention flange of the seal retainer faces the seal retention flange of the shell across the channel to define a seal pocket. An O-ring seal is received in the seal pocket and is held in the seal pocket by the seal retention flanges.