diff --git a/homeassistant/components/synology_dsm/config_flow.py b/homeassistant/components/synology_dsm/config_flow.py
index 4b09e5164513dd..8e2e5ed035806e 100644
--- a/homeassistant/components/synology_dsm/config_flow.py
+++ b/homeassistant/components/synology_dsm/config_flow.py
@@ -208,7 +208,7 @@ async def async_step_2sa(self, user_input, errors=None):
     def _host_already_configured(self, hostname):
         """See if we already have a host matching user input configured."""
         existing_hosts = {
-            entry.data[CONF_HOST] for entry in self._async_current_entries()
+            entry.data.get(CONF_HOST) for entry in self._async_current_entries()
         }
         return hostname in existing_hosts