The invention relates to a magazine for a firearm. The magazine comprises a hollow housing for retaining a plurality of cartridges and a follower arranged inside the hollow housing. The hollow housing has a first side wall, a second side wall opposing the first side wall and a feed opening for feeding the cartridges into the firearm. The first side wall has an outer first side wall surface and an inner first side wall surface and the second side wall has an outer second side wall surface and an inner second side wall surface such that an interior space of the hollow housing is provided between the inner first side wall surface and the inner second side wall surface. The magazine further comprises a stopping member for preventing the follower from escaping out from the hollow housing. The stopping member is arranged to protrude from the inner first side wall surface toward the interior space of the hollow housing.