diff --git a/letsencrypt/auth_handler.py b/letsencrypt/auth_handler.py
index a324dd4b7..659f4b721 100644
--- a/letsencrypt/auth_handler.py
+++ b/letsencrypt/auth_handler.py
@@ -320,12 +320,6 @@ def challb_to_achall(challb, account_key, domain):
             challb=challb, domain=domain, account_key=account_key)
     elif isinstance(chall, challenges.DNS):
         return achallenges.DNS(challb=challb, domain=domain)
-    elif isinstance(chall, challenges.RecoveryContact):
-        return achallenges.RecoveryContact(
-            challb=challb, domain=domain)
-    elif isinstance(chall, challenges.ProofOfPossession):
-        return achallenges.ProofOfPossession(
-            challb=challb, domain=domain)
     else:
         raise errors.Error(
             "Received unsupported challenge of type: %s", chall.typ)