A boot including a sole and an upper, the boot extending length-wise from a heel to a front end, and height-wise from the sole to an upper end, the boot having an opening for foot insertion, and including a lateral portion, a medial portion, as well as a tightening device, the tightening device including a first linkage, a second linkage, as well as connections of the linkages to the upper. The first linkage runs from one portion to the other, in the area of the instep. The second linkage passes through an initial sliding connection located on one of the portions, then through a first intermediate sliding connection located on the other portion, then extends along the upper by going around the heel, between the sole and the upper end, so as to arrive at a fixed end connection located on that of the portions which carries the initial connection.