A button-activated medicament delivery device is presented having a housing arranged to house a medicament container, a vibration sensor configured to measure vibrations induced by the button-activated medicament delivery device during a medicament delivery, a button arranged to initiate medicament delivery from the medicament container, and to activate the vibration sensor when initiating the medicament delivery, and processing circuitry configured to obtain a vibration measurement from the vibration sensor and to compare the vibration measurement with a reference vibration measurement characteristic for the button-activated medicament delivery device during medicament delivery. The processing circuitry is configured to generate a time of measurement of the vibration measurement in case the vibration measurement matches the reference vibration measurement.