The precision editing technologies that have revolutionized DNA editing in the cell nucleus have been unable to reach the mitochondrial genome. Now, researchers have broken this barrier with a new type of molecular editor that can make precise C* G-to-T* A nucleotide changes in mitochondrial DNA. The editor, engineered from a bacterial toxin, enables modeling of disease-associated mtDNA mutations, opening the door to a better understanding of genetic changes associated with cancer, aging, and more.