A fastener used to secure an object on a channel including a channel nut which may be entered into a slot in the channel and then turned about an axis of rotation to extend in a generally crosswise position relative to the slot for engagement of portions of the nut at locations generally adjacent opposite ends of the nut with edges of the channel. A retainer for the nut has a body and a flange integral with the body which may engage the channel at opposite sides of the channel slot for preventing the retainer from being pushed inwardly completely through the slot when the nut is turned to a crosswise position in the channel and when an object is being fastened to the channel. Resiliently deformable spring elements on the body of the retainer are so sized and arranged as to be engageable with the channel for holding the nut in its crosswise position against slippage lengthwise of the channel slot.