diff --git a/dns/client.go b/dns/client.go
index 2c9afbf..8fc5d5f 100644
--- a/dns/client.go
+++ b/dns/client.go
@@ -67,7 +67,7 @@ func (c *Client) Exchange(reqBytes []byte, clientAddr string, preferTCP bool) ([
 	}
 
 	if c.config.NoAAAA && req.Question.QTYPE == QTypeAAAA {
-		reqBytes[2] |= uint8(Response) << 7
+		reqBytes[2] |= uint8(ResponseMsg) << 7
 		return reqBytes, nil
 	}
 
@@ -321,7 +321,7 @@ func MakeResponse(domain, ip string, ttl uint32) (*Message, error) {
 		rdata = ipb
 	}
 
-	m := NewMessage(0, Response)
+	m := NewMessage(0, ResponseMsg)
 	m.SetQuestion(NewQuestion(qtype, domain))
 	rr := &RR{NAME: domain, TYPE: qtype, CLASS: ClassINET,
 		TTL: ttl, RDLENGTH: rdlen, RDATA: rdata}
diff --git a/dns/message.go b/dns/message.go
index 4b24e19..b1b0907 100644
--- a/dns/message.go
+++ b/dns/message.go
@@ -20,10 +20,13 @@ const UDPMaxLen = 512
 // HeaderLen is the length of dns msg header.
 const HeaderLen = 12
 
+// MsgType is the dns Message type.
+type MsgType byte
+
 // Message types.
 const (
-	Query    = 0
-	Response = 1
+	QueryMsg    MsgType = 0
+	ResponseMsg MsgType = 1
 )
 
 // Query types.
@@ -64,7 +67,7 @@ type Message struct {
 }
 
 // NewMessage returns a new message.
-func NewMessage(id uint16, msgType int) *Message {
+func NewMessage(id uint16, msgType MsgType) *Message {
 	if id == 0 {
 		id = uint16(rand.Uint32())
 	}
@@ -194,7 +197,7 @@ type Header struct {
 }
 
 // SetMsgType sets the message type.
-func (h *Header) SetMsgType(qr int) {
+func (h *Header) SetMsgType(qr MsgType) {
 	h.Bits |= uint16(qr) << 15
 }
 
diff --git a/ipset/ipset_linux.go b/ipset/ipset_linux.go
index b5e0111..8cebe8f 100644
--- a/ipset/ipset_linux.go
+++ b/ipset/ipset_linux.go
@@ -30,8 +30,7 @@ func NewManager(rules []*rule.Config) (*Manager, error) {
 	}
 
 	for set := range sets {
-		ipset.Create(set)
-		ipset.Flush(set)
+		createSet(set)
 	}
 
 	// init ipset
@@ -42,10 +41,10 @@ func NewManager(rules []*rule.Config) (*Manager, error) {
 				m.domainSet.Store(domain, r.IPSet)
 			}
 			for _, ip := range r.IP {
-				ipset.Add(r.IPSet, ip)
+				addToSet(r.IPSet, ip)
 			}
 			for _, cidr := range r.CIDR {
-				ipset.Add(r.IPSet, cidr)
+				addToSet(r.IPSet, cidr)
 			}
 		}
 	}
@@ -63,9 +62,23 @@ func (m *Manager) AddDomainIP(domain, ip string) error {
 	for i := len(domain); i != -1; {
 		i = strings.LastIndexByte(domain[:i], '.')
 		if setName, ok := m.domainSet.Load(domain[i+1:]); ok {
-			ipset.Add(setName.(string), ip)
+			addToSet(setName.(string), ip)
 		}
 	}
 
 	return nil
 }
+
+func createSet(s string) {
+	ipset.Create(s)
+	ipset.Flush(s)
+	ipset.Create(s+"6", ipset.OptIPv6())
+	ipset.Flush(s + "6")
+}
+
+func addToSet(s, item string) error {
+	if strings.IndexByte(item, '.') == -1 {
+		return ipset.Add(s+"6", item)
+	}
+	return ipset.Add(s, item)
+}
diff --git a/main.go b/main.go
index 063719e..a7086b1 100644
--- a/main.go
+++ b/main.go
@@ -72,7 +72,6 @@ func main() {
 		if err != nil {
 			log.Fatal(err)
 		}
-
 		go local.ListenAndServe()
 	}