A shipping container has a lid locked using pressure, rather than friction. The container includes front and rear side panels and a lid. The lid has a positive locking tab for engaging with a slot in the front side panel. The tab has a greater length than the slot. An end of the tab and an edge of the lid form a notch therebetween. In an embodiment, a corrugated paperboard blank is folded to approximate the lid to the front side panel. The lid is folded along an angled score line, rotating the tab with respect to the slot so that an end of the tab engages the slot and the front panel at an end of the slot engages the notch. The lid is folded to rotate the tab in the opposite direction; the tab then engages with the slot, the end of the tab extending beyond the slot.