There was an error in J. Exp. Biol.217, 1218-1228. A reference was missing from the reference list. The reference is listed below.

Zelik, K. E., Huang, T. W., Adamczyk, P. G. and Kuo, A. D. (2014). The role of series ankle elasticity in bipedal walking. J. Theor. Biol.346, 75-85.

We apologise to the authors and readers for this omission.