An electrical connector (1) includes an insulative housing (2) defining a plate-like shape with at least one alignment hole (21) extending therethrough in a vertical direction, and a number of electrical contacts (3) secured in the insulative housing (2). A number of spring ribs (211) are integrally formed on the insulative housing (2) and extend into the alignment hole (21). The spring ribs (211) deform in radial direction and circumferential direction of the alignment hole for engaging with an alignment post (41).