The present invention relates to a needle assembly for a drug delivery device comprising of a cup-shaped receptacle having a bottom section supporting a needle element being adapted to penetrate a pierceable seal of a cartridge to be disposed in a cartridge holder of the drug delivery device, wherein the receptacle comprises fastening means for releasably fastening the needle assembly to the cartridge holder, and wherein the fastening means is convertible into a release configuration by way of an elastic deformation of the receptacle.
