An improved broom assembly comprises a head member having an integrally threaded handle receiving opening with a handle threadedly connected therein and including a locking adaptor for preventing inadvertent unthreading of the handle from the head member. The locking adaptor comprises a generally cylindrical collet body member formed independently of the head member and the handle and having a central opening through which the handle slidably extends. The collet body member further includes resilient finger portions extending axially from the body member along the handle in a direction away from the head member. A nut member is threadedly received on the collet body member for movement axially thereof and includes a tapered surface engageable with the finger portions for driving the finger portions radially inward into gripping engagement with the handle. Engagement tabs extend axially between the collet body member and the head member for preventing relative rotation therebetween.