The invention relates to an adaptor for a distal tip of a drug delivery device. The adaptor includes an inner ring having 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 exerted on said conical distal tip limits the axial movement of the adaptor. The adaptor further includes compressing means movable axially with respect to said retaining means between a proximal position, in which said compressing means does not exert a centripetal pressure on said retaining means, and a distal position, in which centripetal pressure is exerted 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.
