In the Comment article 'Buried by bad decisions' (Nature 474, 275–277), the statement “we will save lives by pushing a trolley into a person but not a person into a trolley” refers to an incorrect reference. The correct one is J. D. Greene et al. Science 293, 2105–2108 (2001).

The Comment article 'Crowd control in Rwanda' (Nature 474, 572–573) should have stated that family-planning aid dropped from 30% to 12% of overall health aid, not overall aid.