The V‐ATPase, the major cellular proton pump, is comprised of the peripheral sector V1 catalysing ATP hydrolysis and the membrane integral sector V0 translocating protons. Ten years ago, Andreas Mayer9s group made the surprising observation that proteolipids of the V0 transmembrane sector are implicated in membrane fusion, but deeper analysis proved to be difficult—mostly because V‐ATPase disruption is lethal. Based on a screen for V0 separation‐of‐function mutants in yeast, a study published in this issue of The EMBO Journal now provides direct evidence that the V0 sector regulates the core fusion machinery during the lipid‐mixing step of vacuolar fusion.