Check valve assembly (1, 1′) for a shock absorber (100) comprising a housing (10), said housing (10) comprising a first volume (11), wherein a first pressure (P1) prevails; a second volume (12), wherein a second pressure (P2) prevails; a fluid passage (20) between said first (11) volume and said second (12) volume; and a spool (40) movably arranged in said housing (10) for movement back and forth between an first position, in which a flow of fluid through said fluid passage (20) is allowed, and a second position, in which the spool (40) closes the fluid passage (20). The check valve assembly further comprises a first biasing means (50) configured to bias the spool (40) towards the second position through at least first operational range (OR1) of the spool (40) in which first operational range the fluid passage (20) is open. Also, the check valve assembly comprises a second biasing means (51) configured to bias the spool (40) towards the first position partly through a second operational range (OR2) of the spool (40) in which second operational range (OR2) the fluid passage (20) is closed. The first biasing means forces the spool from its open position at least to its closed position for closing the passage.