The invention relates to a circular knitting machine for the production of knit goods with combed-in fibers, having a rotatable, needle-bearing needle cylinder and a card which has a means for feeding the fibers, a comb-in zone through which the needles pass for the purpose of contactlessly receiving the fibers, and a teasing cylinder rotating at high speed which takes the fibers from the feed means and yields them to the comb-in zone. To prevent thin areas or thick areas from being produced in the finished goods on account of the contactless fiber loading, the circular knitting machine has a protective device (60) which becomes active in the still state of the needle cylinder for the purpose of retaining the already combed-in fiber tufts (57) in the needles (3) which are in the comb-in zone in the still state of the needle cylinder.