Channel fastener for fastening an object to an elongate channel element having a bottom, an upper side opposite the bottom and lateral walls that interconnect the upper side and the bottom, wherein the upper side includes flanges that extend from the lateral walls towards each other and a longitudinal slot defined between the flanges and having a slot width (w s), wherein the fastener comprises: - a metal washer element, which has a bearing face that is arranged for resting against the outer side of the flanges of the channel element, - an oblong metal anchoring element having a width (w a) smaller than the slot width (w s) and a larger length (l a) larger than the slot width (w s), said anchoring element being located on the side of the washer element where the bearing face is located and has longitudinal end portions adapted to engage an inner side of the respective flanges of the channel element, - a support for the anchoring element, which support is made of an elastic material and is connected to the washer element, possibly detachably, and which support bears the anchoring element, the fastener having between the washer element and each longitudinal end portion of the anchoring element an accommodation space which is accessible from the side of the fastener, each accommodation space being adapted for the accommodation of a flange of the channel element, in such a way that the fastener with its oblong anchoring element can be aligned with the longitudinal slot and the anchoring element can be inserted through the longitudinal slot into the channel element, and in such a way that subsequently after turning of the fastener, preferably a quarter turn, the anchoring element extends at an angle, preferably substantially at right angles, relative to the longitudinal slot, so that the flanges of the channel element are located in the accommodation spaces, wherein the anchoring element and the washer element can subsequently be tensioned towards each other wherein the longitudinal end portions of the anchoring element engage the inner side of the flanges of the channel element in order to fix the fastener to the channel element, wherein the support comprises: - a head portion having one or more coupling members, which coupling members, possibly detachably, couple the washer element to the support, - a bottom portion which supports the anchoring element from below, and - connecting legs, each extending from the head portion to the bottom portion below the anchoring element, and connecting the head portion and the bottom portion, wherein the connecting legs extend along a longitudinal side of the oblong anchoring element, wherein the support includes one or more spring members associated with the head portion of the support and adapted to engage an upper side of the flanges, wherein said spring members force the bottom portion with the anchoring element towards the inner side of the flanges of the channel element in a preliminary mounting state in which the flanges are located in the accommodation spaces, characterized in that a blocking finger is formed on an end of at least one of the spring members, wherein said blocking finger extends in said preliminary mounting state beyond the edge of at least one of the flanges and a lateral wall of the channel element, so as to block unintentional rotation of the fastener from said preliminary mounting state. - a metal washer element, which has a bearing face that is arranged for resting against the outer side of the flanges of the channel element, - an oblong metal anchoring element having a width (w a) smaller than the slot width (w s) and a larger length (l a) larger than the slot width (w s), said anchoring element being located on the side of the washer element where the bearing face is located and has longitudinal end portions adapted to engage an inner side of the respective flanges of the channel element, - a support for the anchoring element, which support is made of an elastic material and is connected to the washer element, possibly detachably, and which support bears the anchoring element, - a head portion having one or more coupling members, which coupling members, possibly detachably, couple the washer element to the support, - a bottom portion which supports the anchoring element from below, and - connecting legs, each extending from the head portion to the bottom portion below the anchoring element, and connecting the head portion and the bottom portion, wherein the connecting legs extend along a longitudinal side of the oblong anchoring element,