Nat. Chem. Biol. 10, 1043–1048 (2014); published online 26 October 2014; corrected after print 29 January 2015 and 15 July 2015.

In the version of this article published on 29 January 2015, in Figure 4 the hydroxyl group was depicted in the 3′ position on the deoxyribose ring of the cyclic dinucleotide precursor to 3′3′-cGAMP rather than in the 2′ position and the R group was in the 2′ position rather than in the 3′ position. This error has been corrected in the HTML and PDF versions of the article.