An arrangement for the adjustment of the homogeneity of a basic magnetic field in a magnetic resonance apparatus includes gradient coil support fashioned to support a gradient coil system. The gradient coil support has at least one channel that is fashioned to accommodate an associated shim tray. The shim tray is designed to accommodate ferromagnetic shim elements at predetermined positions in order to adjust the homogeneity of the basic magnetic field of the magnetic resonance apparatus. The shim tray has a first locking element coupled with it. The channel has a second locking element, and the first and second locking element are shaped such that both are positively connected with one another by a force produced by the basic magnetic field of the magnetic resonance apparatus upon activation thereof.