A MEMS resonator comprises a resonator body (34), and an anchor (32) which provides a fixed connection between the resonator body (34) and a support body. A resistive heating element (R1,R2) and a feedback control system are used to maintain the resonator body (34) at a constant temperature. A location for thermally coupling the anchor (32) to the resistive heating element (R1,R2) is selected which has a lowest dependency of its temperature on the ambient temperature during the operation of the feedback control.