An adapter plate may be used to secure a wall mountable connector to a junction box by engaging mounting features of the wall mountable connector. In some cases, the wall mountable connector may be directly secured to a wall via fasteners that extend through the same mounting features of the wall mountable connector. In some cases, the adapter plate may be configured such that the wall mountable connector can be secured to the adapter plate simply by pressing the wall mountable connector into position on the adapter plate, where mounting latches of the adapter plate engage the mounting apertures of the wall mountable connector. The wall mountable connector may be an HVAC wall mountable connector that provides an electrical connection between a plurality of field wires of an HVAC system and corresponding terminals of a removably mounted thermostat.