An adjustable valve control device for an internal combustion engine with a drive shaft, with a camshaft 1 rotated by the drive shaft, and with at least one valve actuated by the camshaft 1 with a specific timing. The valve control device modifies the rotary phase of the camshaft 1 relative to the drive shaft in order to modify the timing of at least one valve and comprises a first rotor 2 which rotates synchronously with the drive shaft, a second rotor 3 which rotates synchronously with the camshaft 1, and a lock bolt 14 for locking the first rotor 2 and the second rotor 3 relative to each other. Fluid is applied to the lock bolt 14 by way of a separate line 15 to lock the rotors and is removed to unlock the rotors.