Ribosomal DNA (rDNA) is essential for ribosome production and is prone to copy number (CN) loss over time. In Drosophila, a process called rDNA magnification restores CN, particularly in the germline. A new paper from the lab shows that rDNA magnification occurs specifically in germline stem cells (GSCs), not in differentiating germ cells, and relies on asymmetric GSC divisions. These findings highlight a key role for GSCs in preserving rDNA CN and ensuring genomic stability across generations.