Timepiece movement including a flexible strip resonator cooperating with a magnetic escapement mechanism, wherein an escape wheel set includes tangential magnetized areas repelling first magnetized areas of an inertial element of the resonator, this movement includes isochronism correction means combining the first magnetized areas and compensating magnets on the escape wheel set, each arranged in proximity to a tangential magnetized area and producing a leakage field in a different direction from that of the field of the tangential magnetized area, the leakage field intensity being low compared to that of the field of the second tangential magnetized area, and this leakage field interacting with one of the first magnetized areas to produce a low variation in the operation of the resonator mechanism.