A retrofit latch adapter is configured to replace a pre-existing roller head latch assembly of a pre-existing exit device. The retrofit latch adapter may include a flat latch head that may provide additional security for a door compared with the pre-existing roller head pre-existing latch assembly. A method of installing such a retrofit latch adapter in a preexisting exist device may include rotationally releasing a pre-existing latch assembly having a roller latch head from the pre-existing exit device; rotating the pre-existing latch assembly to linearly decouple the pre-existing latch assembly from a transmission of the pre-existing exit device; removing the pre-existing latch assembly from the pre-existing exit device; rotating the retrofit latch adapter to linearly couple the retrofit latch adapter to the transmission of the pre-existing exit device; inserting the retrofit latch adapter at least partially into a housing of the pre-existing exit device; aligning the flat latch head with an uppermost portion of the housing of the pre-existing exit device; and rotationally securing the retrofit latch adapter to the pre-existing exit device.