diff --git a/jsonschema/_format.py b/jsonschema/_format.py
index 2231f5e05..4f78110e0 100644
--- a/jsonschema/_format.py
+++ b/jsonschema/_format.py
@@ -270,6 +270,7 @@ def is_ipv6(instance: object) -> bool:
         draft7="hostname",
         draft201909="hostname",
         draft202012="hostname",
+        raises=ValueError,
     )
     def is_host_name(instance: object) -> bool:
         if not isinstance(instance, str):