When coronaviruses jump species—as SARS-CoV-2 is thought to have done from bats or pangolins to humans—they must quickly adapt to their new host. For example, they must evolve to recognize the unique sugar molecules, or glycans, that decorate proteins on the host cell’s surface. Now, researchers reporting in ACS Infectious Diseases have characterized the binding of proteins from several animal and human coronaviruses to glycans called sialic acids, revealing host-specific patterns of binding.