The invention relates to a CIC hearing aid (30) for operation within an ear canal (10) of a user, comprising a lateral module (32), a medial module (34) and a flexible joint assembly (36) connecting the medial end (38) of the lateral module and the lateral end (40) of the medial module in such a manner that the lateral module and the medial module are movable relative to each other in order to follow the shape of the ear canal, wherein the flexible joint assembly is adapted to removably receive an axially extending guide element (68) for temporarily stiffening the flexible joint assembly with regard to bending and/or axial motions when the hearing aid is pushed into the ear canal, and wherein the guide element is adapted to be removed at least from a medial portion (66) of the flexible joint assembly after insertion of the hearing aid.