After adding a new key with ssh-keygen -C '' -N '' -f ssh_host_ed25519_key -t ed25519 And making propellor aware of this with the property Ssh.hostKeys "myhost" [ (SshEd25519, "ssh-ed25519 ...") ] and running cat ssh_host_ed25519_key | propellor --set 'SshPrivKey SshEd25519 ""' 'myhost' propellor --spin myhost I got the following error in my auth.log: error: Could not load host key: /etc/ssh/ssh_host_ed25519_key after adding a newline at the end of /etc/ssh/ssh_host_ed25519_key, everything works well... Is that a bug in propellor?