A delivery tube is inhibited from unintended withdrawal from an infusion pump which has an internal occlusion clamp that clamps the delivery tube to prevent the free flow of fluid through the tube, by overlapping a blocking lip from a compression edge of the occlusion clamp with a restraint surface of an anvil against which the tubing is compressed and by overlapping a blocking projection from the restraint surface with the compression edge. Inhibition is also achieved by positioning an obstruction protrusion adjacent to the compression edge and the blocking lip to resist the application of exterior physical force to force the occlusion clamp from an occluding position to a non-occluding position.
