The invention relates to an adaptor (10) for the distal tip (2) of a drug delivery device comprising : an inner ring (20) comprising retaining means capable of exerting a radial inward force on said distal tip and of switching from a free configuration to a locked configuration in which the radial inward force they exert on said conical distal tip limits the axial movement of the adaptor compressing means (30) movable axially with respect to said retaining means between a proximal position in which said compressing means do not exert a centripetal pressure on said retaining means and a distal position in which they exert a centripetal pressure on said retaining means. The invention further relates to a drug delivery device comprising such an adaptor and to a method for mounting said adaptor on said drug delivery device.
