An electrical connector comprises a housing and a number of terminals residing in the housing. Each of terminals comprises a base portion, a contact portion extending from the base portion, and a retention portion rising from the base portion. The housing defines a number of terminal-mounting holes each with a receiving cavity and an engaging cavity. Along a longitudinal direction of the housing, the width of the receiving cavity is greater than the thickness of the retention portion and the width of the engaging cavity is less than the thickness of the retention portion.