The present invention relates to adaptor (130) for a drug delivery device having a reservoir (12) and a longitudinal tip (20),the adaptor (130) comprising a distal part defining a connecting ring (131) for receiving a connector, and a proximal part defining a mounting ring (133) having an inner surface (134),the mounting ring (133) being configured such that, when the adaptor (130) is mounted around the longitudinal tip (20), an annular space (138) is created between said inner surface (134) and an outer surface (20a) of the longitudinal tip (20), the annular space (138) being able to accommodate an adhesive layer (40) in order to bond said adaptor (130) to said longitudinal tip, where the inner surface (134) comprises protrusions in the form of longitudinal ribs (135). The invention further relates to a drug delivery device comprising such an adaptor.
