Abstract: A plastic food package of base and lid components which have a locking means comprising a locking projection which is stiffened and a locking flap lockingly engagable with the projection. The locking projection in practical constructions is formed by projecting walls which meet to form a peak whereby the projection is stiff. The projection is rigidly held to its component by a stiffening shoulder which supports the projection and itself merges with a sidewall of the component along a junction region which is orientated to prevent movement of projection relative to component. The flap has an aperture and the peak of the projection has to pass through the aperture to lock the flap in a locking position. To effect passage of the peak through the aperture, one of the components needs to be flexed to move the peak into alignment with the aperture.