diff --git a/paramiko/hostkeys.py b/paramiko/hostkeys.py
index e739312ad..da5b66ccc 100644
--- a/paramiko/hostkeys.py
+++ b/paramiko/hostkeys.py
@@ -141,6 +141,8 @@ def add(self, hostname, keytype, key):
             if (hostname in e.hostnames) and (e.key.get_name() == keytype):
                 e.key = key
                 return
+        if not hostname.startswith('|1|') and hash_hostname:
+            hostname = self.hash_host(hostname)
         self._entries.append(HostKeyEntry([hostname], key))
 
     def load(self, filename):