Mitochondria are the only cellular organelle with their own genome, but that genome encodes only a minority of the proteins that mitochondria need to function, with the remainder being produced in the cell and imported into the mitochondrion. That process can go awry in at least three places: the mitochondrial genome, the cellular genome, and the protein import machinery. Now, researchers from the Massachusetts Institute of Technology have identified a surveillance system that prevented glitches in protein import into mitochondria from damaging mitochondria.