© 2020 Kirchdoerfer. The nucleotide analogue remdesivir is an investigational drug for the treatment of human coronavirus infection. Remdesivir is a phosphoramidate prodrug and is known to target viral RNAdependent RNA polymerases. In this issue, Gordon et al. identify that remdesivir acts as a delayed RNA chain terminator for MERS-CoV polymerase complexes.