A wiper coupler adaptor for use in releasably attaching a wiper assembly to a bayonet style wiper arm having an attachment end includes a pair of sidewalls each including a post that extends transversely toward the other to operatively engage structure of a wiper assembly and a deck disposed between the sidewalls that cooperates with a portion of the sidewalls to define a rest adapted to operatively receive the attachment end of the wiper arm. The sidewalls each include a ledge that extends transversely toward the other to operatively engage the attachment end of the wiper arm. The wiper coupler adaptor also includes a locking mechanism including a cantilevered body and a head disposed at a terminal end of the cantilevered body. The head includes a lip depending therefrom that is adapted to extend through an aperture in the base of the attachment end and receive a portion of the base of the attachment end to prevent undesired release of the wiper coupler adaptor from the attachment end of the wiper arm.