In the story ‘Speedy drills start hunt for oldest ice’ (Nature 540, 18–19; 2016), the size of the borehole to be drilled by the US RAID was wrong. It will be about 8 cm, and so roughly the same size as the other planned holes. The story should also have noted that as well as Jeffrey Severinghaus, the US project is co-led by John Goodge of the University of Minnesota, Duluth.