A portable surgical instrument (PSI) includes a shaft extending therefrom. An end effector operably supported at the distal end of the shaft includes a pair of jaw members. One or both of the jaw members is activatable to treat tissue. A selectively removable generator pivotally couples to the housing to energize the activatable jaw member. The generator defining one or more apertures at a distal end thereof and a pivot member disposed at a proximal end thereof. A locking mechanism configured to operably couple to the elongated shaft of the housing includes one or more locking fingers configured to releasably couple to the one or more apertures disposed at the distal end of the generator such that generator is selectively and removably engageable with the housing of the portable surgical instrument.