A generator (5) for a wind turbine (1) is disclosed. The generator (5) comprises a rotor (3) configured to rotate about a rotational axis, and at least one stator (4) arranged next to the rotor (3). Each stator (4) comprises at least two subunits (8), the subunits (8) being arranged side-by-side along a moving direction of the rotor (3). Each subunit (8) comprises at least one flux-generating module (9) facing the rotor (3) but spaced therefrom, thereby defining an air gap between the rotor (3) and each flux-generating module (9). The subunits (8) are movable relative to each other along a direction which is substantially transverse to the moving direction of the rotor (3). This allows a subunit (8) to move in a manner which adjusts the air gap without affecting the position and the air gap of a neighboring subunit (8). Thereby variations in the rotor (3) can be compensated and a uniform and constant air gap can be maintained. The invention further provides a wind turbine (1) comprising such a generator (5) and a method for performing service on a generator (5).