The present invention relates to a drug delivery device (100) comprising:- a reservoir (10) for a product, said reservoir having a distally projecting end-piece (20) defining an axial passageway for the transfer of the product, said end-piece having a distal portion (23),- an adaptor (30) having a collar (31) engageable around said end-piece,- securing means (13, 24) for locking the axial movement of said collar with respect to said end-piece, whereinsaid adaptor further comprises a foldable element (36, 34) capable of going from a folded configuration in which said foldable element substantially surrounds said distal portion of said end-piece, and an unfolded configuration, in which said foldable element leaves said distal portion uncovered. The invention also relates to such an adaptor.
