In the Commentary 'Unidirectional light propagation at exceptional points' (Nature Mater. 12 175–177; 2013), the volume number in ref. 6 was incorrect; the reference should have read 'Feng, L. et al. Nature Mater. 12, 108–113 (2013)'. This error has been corrected in the HTML and PDF versions, after print 29 April 2013.