A method for securing a cartridge (4) to a body (2) for a drug delivery device (1 ) is provided comprising the step of securing the cartridge (4) to the body (2) by means of a releasable connection (7) to prevent accidental relative movement between the cartridge (4) and the body (2) during assembly of the device (1 ). Afterwards, the releasable connection (7) is modified irreversably into a non-releasable connection such that the cartridge (4) is permanently secured to the body (2). Furthermore, an assembly for a drug delivery device (1 ) is provided comprising a cartridge (4), a body (2), a first connection means (9) and a second connection means. The first connection means (9) and the second connection means 17 are configured to mechanically cooperate to form a releasable connection (7). The releasable connection (7) is suitable for releasably securing the cartridge (4) to the body (2). The releasable connection (7) prevents accidental relative movement between the cartridge (4) and the body (2) during assembly of the device (1 ). The first connection means (9) and the second connection means 17 are irreversably non-releasably secured to each other.La présente invention concerne un procédé permettant de fixer une cartouche (4) sur un corps (2) pour un dispositif (1) dadministration de médicament, lequel procédé comprend les étapes qui consistent à fixer la cartouche (4) au corps (2) au moyen dun raccord amovible (7) afin dempêcher tout mouvement relatif accidentel entre la cartouche (4) et le corps (2) pendant lassemblage du dispositif (1). Ensuite, le raccord amovible (7) est modifié de manière irréversible en un raccord non amovible, de telle sorte que la cartouche (4) est fixée de manière permanente au corps (2). Dautre part, linvention concerne un ensemble pour un dispositif (1) dadministration de médicament comprenant une cartouche (4), un corps (2), un premier moyen de raccordement (9) et un second moyen de raccordement. Le premier moyen de raccordement (9)
