A compression-release brake system comprises an exhaust rocker arm, an actuation piston slidable in a piston bore in the exhaust rocker arm so as to press an exhaust valve, a supply conduit formed within the exhaust rocker arm, and an exhaust valve reset device mounted to the exhaust rocker arm. The actuation piston defines an actuation piston cavity within the actuation piston bore between the piston bore and the actuation piston. The exhaust valve reset device includes a reset check valve disposed between the supply conduit and the actuation piston cavity to hydraulically lock the actuation piston cavity by closing the reset check valve when a pressure of the hydraulic fluid within the actuation piston cavity exceeds the pressure of the hydraulic fluid in the supply conduit. The reset check valve is biased closed by the pressure of the hydraulic fluid within the actuation piston cavity during the brake-on mode.