Nature 521, 328–331 (2015); doi:10.1038/nature14440

In this Letter, the superscript in the ultraviolet luminosity was listed incorrectly as ‘−41’ rather than ‘41’ in the last sentence of the second paragraph from the bottom in the left column of page 1. It should have read LUV ≈ 3 × 1041 erg s−1. This has been corrected online.