  A revised rotation-vibration line list for the combined hydrogen cyanide
(HCN) / hydrogen isocyanide (HNC) system is presented. The line list uses {\it
ab initio} transition intensities calculated previously (Harris et al., ApJ,
2002, 578, 657) and extensive datasets of recently measured experimental energy
levels (Mellau, J. Chem. Phys. and J. Mol. Spectrosc. 2010-2011). The resulting
line list has significantly more accurate wavelengths than previous ones for
these systems. An improved value for the separation between HCN and HNC is
adopted leading to an approximately 25%\ lower predicted thermal population of
HNC as a function of temperature in the key 2000 to 3000 K region.
Temperature-dependent partition functions and equilibrium constants are
presented. The line lists are validated by comparison with laboratory spectra
and are presented in full as supplementary data to the article and at
\url{www.exomol.com}.
