The invention relates to a child safety seat (100) comprising at least a first (104), a second (104) and a third locking mechanism (106) each being adapted for releasably locking the seat (100) to a vehicle at a respective anchorage point, wherein the anchorage points of the first locking mechanism (104) and the second locking mechanism (104) are arranged on a line, the anchorage point of the third locking mechanism (106) being spaced apart from the line a seat surface (101) of the seat (100), the seat surface (101) providing a sitting area of the seat (100), the third locking mechanism (106) being adjustable in height relative to the seat surface (101) and a coupling member (202), the third locking mechanism (106) being secured to the seat (100) via the coupling member (202), the coupling member (202) being height adjustable to enable the height adjustability of the third locking mechanism (106).