A connector assembly includes a housing, a plurality of contact modules received in the housing, and a pin spacer coupled to the contact modules. Each contact module has a plurality of contacts each including a pin extending from a bottom of the corresponding contact module. The pin spacer has a plurality of pin holes extending through the pin spacer. The pin holes receive corresponding pins for mounting to the circuit board. The pin spacer holds relative positions of the pins. The pin spacer has side edges at opposite sides of the pin spacer and lugs extending from the top of the pin spacer proximate to the sides of the pin spacer. The lugs block entry into a space defined between the bottoms of the contact modules and the top of the pin spacer.