An adaptor for mounting a pin-type wiper blade on a hook-type wiper arm includes first and second walls separated by a shouldered pin and a pair of struts. A U-shaped spring clip is disposed over the shouldered pin, the spring clip is disposed over the shouldered pin, the spring clip having outwardly directed tangs in the legs thereof which are captured within apertures disposed in the hooked end of the hook-type wiper arm. Each of the walls of the adaptor includes an opening, the openings being aligned with apertures in the primary yoke of the wiper blade such that a retention pin can pass therethrough and be captured by a spring clip in the wiper blade.