CIM-834 is an orally active, selective inhibitor that targets the coronavirus membrane protein (M protein), exhibiting potent inhibition of viral assembly in both SARS-CoV-2 and SARS-CoV. It binds non-covalently to the short form of the M protein (Mshort), stabilizing it and preventing its conformational change to the long form (Mlong) necessary for virion assembly, thus blocking virus particle formation. CIM-834 holds potential for research in COVID-19 and other coronavirus infections.