diff --git a/config/config.go b/config/config.go
index a4f0e942..d170617e 100644
--- a/config/config.go
+++ b/config/config.go
@@ -115,7 +115,7 @@ type Tun struct {
 	DNSHijack           []netip.AddrPort `yaml:"dns-hijack" json:"dns-hijack"`
 	AutoRoute           bool             `yaml:"auto-route" json:"auto-route"`
 	AutoDetectInterface bool             `yaml:"auto-detect-interface" json:"auto-detect-interface"`
-	TunAddressPrefix    *netip.Prefix    `yaml:"-" json:"-"`
+	TunAddressPrefix    netip.Prefix     `yaml:"-" json:"-"`
 }
 
 // IPTables config
@@ -910,9 +910,11 @@ func parseTun(rawTun RawTun, general *General, dnsCfg *DNS) (*Tun, error) {
 		dnsHijack = append(dnsHijack, addrPort)
 	}
 
-	var tunAddressPrefix *netip.Prefix
+	var tunAddressPrefix netip.Prefix
 	if dnsCfg.FakeIPRange != nil {
-		tunAddressPrefix = dnsCfg.FakeIPRange.IPNet()
+		tunAddressPrefix = *dnsCfg.FakeIPRange.IPNet()
+	} else {
+		tunAddressPrefix = netip.MustParsePrefix("198.18.0.1/16")
 	}
 
 	return &Tun{
diff --git a/listener/tun/tun_adapter.go b/listener/tun/tun_adapter.go
index 35a9d0a6..9d0cad1b 100644
--- a/listener/tun/tun_adapter.go
+++ b/listener/tun/tun_adapter.go
@@ -26,7 +26,7 @@ import (
 func New(tunConf *config.Tun, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.PacketAdapter) (ipstack.Stack, error) {
 
 	var (
-		tunAddress = netip.Prefix{}
+		tunAddress = tunConf.TunAddressPrefix
 		devName    = tunConf.Device
 		stackType  = tunConf.Stack
 		autoRoute  = tunConf.AutoRoute
@@ -38,10 +38,6 @@ func New(tunConf *config.Tun, tcpIn chan<- C.ConnContext, udpIn chan<- *inbound.
 		err error
 	)
 
-	if tunConf.TunAddressPrefix != nil {
-		tunAddress = *tunConf.TunAddressPrefix
-	}
-
 	if devName == "" {
 		devName = generateDeviceName()
 	}