A method for operating a Coriolis mass flowmeter having at least one measuring tube, at least one oscillation generator, at least one oscillation sensor and at least one strain sensor. The oscillation generator is actuated with an oscillation excitation signal and the measuring tube is excited to oscillation by the oscillation generator, the oscillation of the measuring tube is detected by the oscillation sensor and an oscillation sensor signal is generated. The strain sensor is mechanically coupled to the measuring tube via a connection. A change of the mechanical coupling via the connection can be determined by the oscillation of the measuring tube being measured by the strain sensor and a strain sensor signal generated representing oscillation of the measuring tube, a correlation between the strain sensor signal and an oscillation signal representing the oscillation of the measuring tube is identified, and a temporal change of the correlation is determined.