Check presence of a hostname under custom port in known_hosts

I need to add a check if the hostname is already present in the known_hosts file. Normally I would do something like that: ssh-keygen -H -F hostname However, that does not seem to work for me in this particular case. I connect to the host using port 2102, like that: ssh user@myhost -p 2102 I was asked to add the hostname to the known_hosts file, I say yes. After that I run ssh-keygen -H -F myhost but receive empty result. To make the matter worse, the known_hosts is hashed. That works perfectly with port 22, so if I login to ssh user@myotherhost, save the known host and run ssh-keygen -H -F myotherhost I receive the exact line from the file. So, how can I adjust the command to work with port 2102?