diff --git a/nsupdate/main/dnstools.py b/nsupdate/main/dnstools.py
index 4daff10..a6529f1 100644
--- a/nsupdate/main/dnstools.py
+++ b/nsupdate/main/dnstools.py
@@ -214,6 +214,8 @@ def update(fqdn, ipaddr, ttl=60):
         # maybe could be caused by secondary DNS Timeout and master still ok?
         # assume the update is OK...
         ok = True
+    except dns.message.UnknownTSIGKey:
+        raise DnsUpdateError("UnknownTSIGKey")
     if ok:
         # only send an update if the ip really changed as the update
         # causes write I/O on the nameserver and also traffic to the
diff --git a/nsupdate/management/commands/domains.py b/nsupdate/management/commands/domains.py
index 26ff7d7..47ffbe5 100644
--- a/nsupdate/management/commands/domains.py
+++ b/nsupdate/management/commands/domains.py
@@ -3,6 +3,7 @@ dealing with domains (Domain records in our database)
 """
 
 import dns.resolver
+import dns.message
 
 from django.core.management.base import BaseCommand
 from django.core.mail import send_mail
@@ -60,7 +61,7 @@ def check_dns(domain):
         query_ns(fqdn, 'SOA', prefer_primary=True)
         queries_ok = True
     except (dns.resolver.Timeout, dns.resolver.NoNameservers,
-            dns.resolver.NXDOMAIN, dns.resolver.NoAnswer, NameServerNotAvailable):
+            dns.resolver.NXDOMAIN, dns.resolver.NoAnswer, NameServerNotAvailable, dns.message.UnknownTSIGKey):
         # note: currently the domain is also set to unavailable as a
         # side effect in query_ns()
         queries_ok = False