A toolholder assembly includes a toolholder having a rearwardly facing toolholder shank, a base member having a bore configured for receiving the toolholder shank, a lock rod with an axial forward and an axial rearward end, at least one locking member in communication with the axial forward end of the lock rod, and a flexible canister configured for receipt in the bore of the base member. The flexible canister includes at least one flexible feature that reduces a stiffness (i.e., increases flexibility) of the flexible canister. In one aspect, the flexible feature is a slot proximate a locking passageway of the canister.