A cushion (26) for a patient interface device includes a support wall portion having a first edge and an opposite second edge, and a sealing flap (40) extending in a cantilevered fashion inwardly from the second edge and toward a longitudinal axis of the cushion such that when the patient interface device is donned a portion of the face of the user will engage the top outer surface of the sealing flap to form a seal. The sealing flap includes a corrugated portion (56), wherein the corrugated portion commences at a distal edge of the sealing flap and extends toward a proximal edge of the sealing flap along at least a portion of a width of the sealing flap. The corrugated portion includes a series of alternating furrows and ridges.
