The invention relates to a foot prop adapted to be attached to a child safety seat, comprising an elongate component, comprising an upper portion and a lower portion, wherein the lower portion is slidable relative to the upper portion in longitudinal direction of the elongate component. The foot prop is configured such that a force applied in the longitudinal direction causes the lower portion to automatically move away from the upper portion whenever the force exceeds a predetermined threshold, so that the length of the elongate component is increased; and the foot prop is configured such that the lower and the upper portion are releasably blocked against relative movement towards one another. The invention further relates to a seat base and a child safety seat comprising a foot prop.