The present invention relates to a filter frame for receiving a media pack, the filter frame comprising a front plate, and first and second gable plates arranged at opposite ends of the front plate. The front plate comprises a groove at each of the ends and a front edge portion of each gable plate is received in a respective one of the grooves. Each gable plate comprises a retainment member arranged at the front edge portion, which retainment member has been engaged with a complementary retainment member of the front plate. The invention also relates to a filter assembly and a method for assembling a filter frame.