diff --git a/acme/acme/challenges.py b/acme/acme/challenges.py
index 1ffc6cc99..fbb2e7418 100644
--- a/acme/acme/challenges.py
+++ b/acme/acme/challenges.py
@@ -34,7 +34,7 @@ class DVChallenge(Challenge):  # pylint: disable=abstract-method
     """Domain validation challenges."""
 
 
-class UnrecognizedChallenge(DVChallenge):
+class UnrecognizedChallenge(Challenge):
     """Unrecognized challenge."""
     typ = "unknown"