C-shaped permanent magnets offer a compromise between sample accessability and field strength as well as homogeneity compared to single-sided devices or Halbach arrays. A new approach to passively shim C-shaped dipole magnets is presented. It relies on the magnet poles being constructed from a set of adjustable magnet elements. Two pole concepts are introduced, which allow the correction of the field profile and passively shim the magnet without the need of additonal pole shoes or shim pieces.