An ultrasonic surgical instrument is disclosed including an ultrasonic blade, an ultrasonic transducer operably coupled to the ultrasonic blade, and a control circuit. The ultrasonic transducer is configured to transmit ultrasonic vibrations to the ultrasonic blade based on a drive signal. The control circuit is configured to provide the drive signal to the ultrasonic transducer, monitor a vibration frequency of the drive signal, and modify the drive signal based on a change in the vibration frequency of the drive signal.