The invention relates to a child safety seat (100) comprising an integral harness belt (106) for restraining a child in the child safety seat (100), a deflector (102) for the harness belt (106), an elastic mechanism (104) adapted for forcing the deflector (102) from a first position (114) to a second position (112), the harness belt (106) being guided by the deflector (102), wherein due to the guidance by the deflector (102) the harness belt (106) length available for buckling in the child is shorter in the second position (112) than in the first position (114), a latch mechanism transferable between a blocking position and a release position, the latch mechanism being adapted for blocking in the blocking position the deflector (102) against a movement toward the second position (112) and for releasing in the release position the deflector (102) for a movement induced by the forcing toward the second position (112), and a release mechanism adapted for transferring the latch mechanism from the blocking position to the release position upon receiving a trigger signal.