Correction to: Nature Biotechnology https://doi.org/10.1038/nbt.3811 published online 27 February 2017.

In the version of the Supplementary information initially published alongside this article, in the second two sentences of Supplementary Fig. 1 there was a mistake in the text originally reading “The codon marked in yellow indicates the D10A substitution in the HNH domain of Cas9. The H840A substitution in RuvC domain of Cas9 is shown in purple” which has now been revised to “The codon marked in yellow indicates the D10A substitution in the RuvC domain of Cas9. The H840A substitution in HNH domain of Cas9 is shown in purple.” The Supplementary information has been replaced online.