Abstract: A beam-blocking safety shutter (100) is mounted in a fiber-optic adapter housing (500) that mates with a standard fiber-optic male connector of the type with a fiber-containing ferrule protruding from a forward end. The shutter is rotatably mounted in the insertion passage on a shaft (300) and held in the light-blocking position by a closing spring (200). The shutter has two shoulders (130) extending forward from a backplate portion (120) of the shutter. The shoulders, placed to either side of the ferrule's path in the insertion passage, hit the body of the inserted connector and take the force that opens the shutter, so that the ferrule is protected from contact. The shoulders preferably are deeper than the distance the ferrule extends from the connector body. The ends of the shaft protrude from the sides of the shutter. The protruding ends are slid into dead-end grooves in the housing and held there by a U-shaped clip forced into the grooves.