Nat. Chem. Biol. 9, 533–534 (2013); published online 19 August 2013; corrected after print 25 September 2013

In the version of this article initially published, the sentence “Three papers now report that cGAS produces a new type of second messenger molecule1,4,5” did not also attribute the finding to reference 6. The error has been corrected in the HTML and PDF versions of the article.