A pneumatic fastener includes a housing and a handle coupled to the housing. The handle defines an inlet channel for delivering compressed gas to the housing. A trigger valve is in communication with the inlet channel and configured to actuate the pneumatic fastener. A fastener driving assembly is disposed within the housing. The fastener driving assembly includes a cylinder and a piston that reciprocates within the cylinder to drive a fastener. A valve piston is coupled to the fastener driving assembly. Actuation of the valve piston causes compressed air to drive the piston within the cylinder to drive the fastener. An outer cap is coupled to the housing and an inner cap is disposed at least partially within the outer cap. The inner cap includes an opening in communication with the trigger valve for porting the compressed air to a region above the valve piston.