An extension frame for a transport box or a pallet includes two long sides, and two collapsible transverse sides. An angle piece is formed on one of the transverse sides or on one of the long sides, with the angle piece having a free end forming a hinge with a free end of an adjacent long side or transverse side. The hinge has in the open state and the collapsed state a locking position in which the long side and the adjacent transverse side are engageable.