A hydraulic anchor is coupled to a packer subassembly of a tool string. The hydraulic anchor, when actuated by fluid pressure, engages the surrounding wellbore, holding the tool string in place within the wellbore. A packer may then be actuated, held in position within the wellbore by the hydraulic anchor. In some embodiments, an inflatable packer may be held in the desired location by the hydraulic anchor. In some embodiments, a straddle packer assembly may be held in place by the hydraulic anchor. In some embodiments, a swellable packer may be held in place during the swelling process by the hydraulic anchor.