Every minute, each human cell constructs up to 7,500 ribosomes — essential intracellular factories that decode instructions from genes to make all the proteins in the body. Ribosomes are assembled from four distinct ribosomal RNA (rRNA) molecules and 80 different proteins, which form small and large subunits, in a complex process involving more than 200 assembly factors. A better understanding of the underlying mechanisms might help to explain the devastating consequences of genetic mutations known as ribosomopathies that affect this assembly pathway. Writing in Nature, Shao et al.1 identify an unexpected role for the enzyme DNA-dependent protein kinase (DNA-PK) — a core component of the machinery for repairing DNA double-strand breaks (DSBs) — in the early steps of ribosome assembly.