diff --git a/acme/dns_challenge.go b/acme/dns_challenge.go
index d9ff3e7e..2fe81c24 100644
--- a/acme/dns_challenge.go
+++ b/acme/dns_challenge.go
@@ -197,7 +197,7 @@ func FindZoneByFqdn(fqdn, nameserver string) (string, error) {
 		return zone, nil
 	}
 
-	// Query the authorative nameserver for a hopefully non-existing SOA record,
+	// Query the authoritative nameserver for a hopefully non-existing SOA record,
 	// in the authority section of the reply it will have the SOA of the
 	// containing zone. rfc2308 has this to say on the subject:
 	//   Name servers authoritative for a zone MUST include the SOA record of