diff --git a/edns.go b/edns.go
index d2bfecbb..f98224b3 100644
--- a/edns.go
+++ b/edns.go
@@ -257,8 +257,7 @@ func (e *EDNS0_SUBNET) pack() ([]byte, error) {
 }
 
 func (e *EDNS0_SUBNET) unpack(b []byte) error {
-	lb := len(b)
-	if lb < 4 {
+	if len(b) < 4 {
 		return ErrBuf
 	}
 	e.Family, _ = unpackUint16(b, 0)
@@ -285,6 +284,8 @@ func (e *EDNS0_SUBNET) unpack(b []byte) error {
 		e.Address = net.IP{addr[0], addr[1], addr[2], addr[3], addr[4],
 			addr[5], addr[6], addr[7], addr[8], addr[9], addr[10],
 			addr[11], addr[12], addr[13], addr[14], addr[15]}
+	default:
+		return errors.New("dns: bad address family")
 	}
 	return nil
 }