The present invention relates to a device for determining the fill level of a flexible medicine reservoir (1), comprising- a stop surface designed and arranged such that the stop surface contacts the flexible medicine reservoir while the reservoir is filled above a predetermined level,- a release detector (2) arranged on the stop surface and configured to generate an output signal indicative of the contact between the slop surface and the flexible medicine reservoir being released, and- a processing unit (16) for determining the fill level of the flexible medicine reservoir from the output signal of the release detector.
