A modified glue flap of a folding carton blank for preventing glue from being squeezed out during the step of adhering the glue flap to the opposite end panel. The face of the glue flap engaged by the glue back-up wheel includes a protrusion near the trailing edge of the flap. Engagement of the protrusion by the back-up wheel causes the glue wheel to skip the trailing area of the flap. The absence of glue in this area prevents glue from being squeezed out when sealing pressure is subsequently applied to the glue flap and the opposite end panel. The protrusion may take the form of an embossed ridge, forming a channel on the opposite side of the protrusion for receiving any excess glue which would have been squeezed out.