An anchor-handling device comprises a housing shaped to define a channel having an anchor-storage zone and a proximal opening. An anchor driver comprises an anchor-engaging head, the anchor-engaging head being dimensioned to be advanceable through the proximal opening toward the anchor-storage zone. A tissue anchor is stored in the anchor-storage zone, and comprises a coupling head configured to be locked to the anchor-engaging head. The tissue anchor is movable out of the anchor-storage zone toward the proximal opening in response to a proximally-directed force being applied to the tissue anchor by the anchor driver. The anchor-handling device comprises an element that serves as an indicator of movement of the tissue anchor out of the anchor-storage zone toward the proximal opening, by moving in response to the proximally-directed force such that at least part of the element protrudes out of the housing. Other embodiments are also described.