The present invention relates to a method of testing the mechanical integrity of a cartridge (10) containing a medicament and being arranged inside a drug delivery device (20). The invention also relates to a testing arrangement and to a respective drug delivery device, wherein the method comprises the steps of: acoustically stimulating the cartridge (10), measuring of the cartridges (10) acoustic response (60) to the acoustic stimulation (32), comparing the acoustic response (60) with a standard response (62) of an intact cartridge (10), and determining the mechanical integrity of the cartridge (10) on the basis of the comparison.
