diff --git a/common/net/address.go b/common/net/address.go
index 85e7e6c8..1a163319 100644
--- a/common/net/address.go
+++ b/common/net/address.go
@@ -8,8 +8,9 @@ import (
 )
 
 var (
-	LocalHostIP = IPAddress([]byte{127, 0, 0, 1})
-	AnyIP       = IPAddress([]byte{0, 0, 0, 0})
+	LocalHostIP     = IPAddress([]byte{127, 0, 0, 1})
+	AnyIP           = IPAddress([]byte{0, 0, 0, 0})
+	LocalHostDomain = DomainAddress("localhost")
 )
 
 type AddressFamily int
@@ -156,3 +157,22 @@ func (v *IPOrDomain) AsAddress() Address {
 	}
 	panic("Common|Net: Invalid address.")
 }
+
+func NewIPOrDomain(addr Address) *IPOrDomain {
+	switch addr.Family() {
+	case AddressFamilyDomain:
+		return &IPOrDomain{
+			Address: &IPOrDomain_Domain{
+				Domain: addr.Domain(),
+			},
+		}
+	case AddressFamilyIPv4, AddressFamilyIPv6:
+		return &IPOrDomain{
+			Address: &IPOrDomain_Ip{
+				Ip: addr.IP(),
+			},
+		}
+	default:
+		panic("Unknown Address type.")
+	}
+}
diff --git a/proxy/dokodemo/dokodemo_test.go b/proxy/dokodemo/dokodemo_test.go
index b154e641..31ab436f 100644
--- a/proxy/dokodemo/dokodemo_test.go
+++ b/proxy/dokodemo/dokodemo_test.go
@@ -54,11 +54,7 @@ func TestDokodemoTCP(t *testing.T) {
 
 	port := v2net.Port(dice.Roll(20000) + 10000)
 	dokodemo := NewDokodemoDoor(&Config{
-		Address: &v2net.IPOrDomain{
-			Address: &v2net.IPOrDomain_Ip{
-				Ip: v2net.LocalHostIP.IP(),
-			},
-		},
+		Address:     v2net.NewIPOrDomain(v2net.LocalHostIP),
 		Port:        uint32(tcpServer.Port),
 		NetworkList: v2net.Network_TCP.AsList(),
 		Timeout:     600,
@@ -128,11 +124,7 @@ func TestDokodemoUDP(t *testing.T) {
 
 	port := v2net.Port(dice.Roll(20000) + 10000)
 	dokodemo := NewDokodemoDoor(&Config{
-		Address: &v2net.IPOrDomain{
-			Address: &v2net.IPOrDomain_Ip{
-				Ip: v2net.LocalHostIP.IP(),
-			},
-		},
+		Address:     v2net.NewIPOrDomain(v2net.LocalHostIP),
 		Port:        uint32(udpServer.Port),
 		NetworkList: v2net.Network_UDP.AsList(),
 		Timeout:     600,
diff --git a/proxy/freedom/freedom_test.go b/proxy/freedom/freedom_test.go
index 30c715cc..557d764c 100644
--- a/proxy/freedom/freedom_test.go
+++ b/proxy/freedom/freedom_test.go
@@ -70,11 +70,7 @@ func TestIPResolution(t *testing.T) {
 	space.BindApp(router.APP_ID, r)
 	dnsServer := dns.NewCacheServer(space, &dns.Config{
 		Hosts: map[string]*v2net.IPOrDomain{
-			"v2ray.com": {
-				Address: &v2net.IPOrDomain_Ip{
-					Ip: []byte{127, 0, 0, 1},
-				},
-			},
+			"v2ray.com": v2net.NewIPOrDomain(v2net.LocalHostIP),
 		},
 	})
 	space.BindApp(dns.APP_ID, dnsServer)
diff --git a/tools/conf/common.go b/tools/conf/common.go
index 28fa293b..d003142b 100644
--- a/tools/conf/common.go
+++ b/tools/conf/common.go
@@ -51,19 +51,7 @@ func (v *Address) UnmarshalJSON(data []byte) error {
 }
 
 func (v *Address) Build() *v2net.IPOrDomain {
-	if v.Family().IsDomain() {
-		return &v2net.IPOrDomain{
-			Address: &v2net.IPOrDomain_Domain{
-				Domain: v.Domain(),
-			},
-		}
-	}
-
-	return &v2net.IPOrDomain{
-		Address: &v2net.IPOrDomain_Ip{
-			Ip: []byte(v.IP()),
-		},
-	}
+	return v2net.NewIPOrDomain(v.Address)
 }
 
 type Network string
diff --git a/v2ray.go b/v2ray.go
index fd84c543..3b593c7b 100644
--- a/v2ray.go
+++ b/v2ray.go
@@ -63,11 +63,7 @@ func NewPoint(pConfig *Config) (*Point, error) {
 		dnsServer := dns.NewCacheServer(space, &dns.Config{
 			NameServers: []*v2net.Endpoint{
 				{
-					Address: &v2net.IPOrDomain{
-						Address: &v2net.IPOrDomain_Domain{
-							Domain: "localhost",
-						},
-					},
+					Address: v2net.NewIPOrDomain(v2net.LocalHostDomain),
 				},
 			},
 		})