The invention relates to a ball joint (10) for a wiper system, comprising a ball shell (12), a ball head (14) within the ball shell (12), a hinged rod (16) into which the ball shell (12) is inserted, and a securing means (18), wherein the securing means (18) engages around the hinged rod (16), in order to reduce an opening (20) in the ball shell (12) to a blocking distance (d), such that the ball head (15) can be removed from the ball shell (12). The invention further relates to a method for assembling the ball joint (10).