The present invention concerns an assembly for holding or supporting a timepiece balance spring including a balance spring stud and a stud-holder, wherein said stud-holder includes: a base comprising an upper face and a lower face extending along a longitudinal axis; characterized in that the base includes a lug of non-constant shape protruding from one of the faces, said assembly further comprising a holding plate including a first opening and a second opening separated by a deformable arm, with the stud engaging in the second opening.