Hydraulic valve (100, 1000) for a camshaft adjuster, which hydraulic valve comprises the following: a piston arrangement which comprises a piston which is axially movable in a central opening of a valve housing; and a first check valve and a second check valve, which are arranged in the piston and which prevent a hydraulic fluid which is flowing through the piston arrangement from unintentionally flowing out of an interior space of the piston arrangement in a first fluid flow through a first throughflow opening of the piston in the direction of a first working port and in a second fluid flow through a second throughflow opening of the piston in the direction of a second working port; wherein the piston arrangement has a start position, a middle position and an end position, wherein the hydraulic fluid flows from the first working port to the second working port when the piston arrangement is in the start position, wherein the hydraulic fluid cannot flow between the first working port and the second working port when the piston arrangement is in the middle position, wherein the hydraulic fluid flows from the second working port to the first working port when the piston arrangement is in the end position, wherein the first working port and the second working port are opened and closed in a manner dependent on a position of the piston, wherein the hydraulic valve (100, 1000) furthermore comprises a supply port which is arranged at an end of the hydraulic valve (100, 1000), characterized in that the check valves (32, 33) are arranged in axially displaceable fashion in the piston, wherein one of the check valves (32, 33) can be placed in contact against a supply or check valve pipe (34, 43) arranged in the piston. a piston arrangement which comprises a piston which is axially movable in a central opening of a valve housing; and a first check valve and a second check valve, which are arranged in the piston and which prevent a hydraulic fluid which is flowing through the piston arrangement from unintentionally flowing out of an interior space of the piston arrangement in a first fluid flow through a first throughflow opening of the piston in the direction of a first working port and in a second fluid flow through a second throughflow opening of the piston in the direction of a second working port; wherein the piston arrangement has a start position, a middle position and an end position, wherein the hydraulic fluid flows from the first working port to the second working port when the piston arrangement is in the start position, wherein the hydraulic fluid cannot flow between the first working port and the second working port when the piston arrangement is in the middle position, wherein the hydraulic fluid flows from the second working port to the first working port when the piston arrangement is in the end position, wherein the first working port and the second working port are opened and closed in a manner dependent on a position of the piston, wherein the hydraulic valve (100, 1000) furthermore comprises a supply port which is arranged at an end of the hydraulic valve (100, 1000), characterized in that the check valves (32, 33) are arranged in axially displaceable fashion in the piston, wherein one of the check valves (32, 33) can be placed in contact against a supply or check valve pipe (34, 43) arranged in the piston.