The present invention relates to a medicament container retaining mechanism (32) for a medicament delivery device (10) comprising at least one flexible retaining member (34) arranged to a housing part (12) of said medicament delivery device (10), which housing part (12) is configured to receive a generally tubular medicament container (22) therein and wherein said at least one flexible retaining member (34) is configured to interact with an outer surface of said medicament container (22) received therein, whereby said at least one flexible retaining member (34) is configured to exert lateral clamping forces to said medicament container (22) to prevent movement in the generally lateral direction of said medicament container in said housing part (12).