The present invention relates to a dose setting mechanism for a drug delivery device and a method of using same. The mechanism comprises a drug delivery device housing, a dose dial sleeve positioned at least partly in the housing and being rotatable during dose setting and dose delivery, a clutch rotatable during dose setting and non-rotatable during dose delivery, and a clutch nut, that is threadedly engaged with the clutch and is splined to the housing to prevent rotation of the clutch nut.