diff --git a/app/router/lua.go b/app/router/lua.go
index 259f3a96b..8e723b954 100644
--- a/app/router/lua.go
+++ b/app/router/lua.go
@@ -3,6 +3,7 @@ package router
 import (
 	"context"
 	"runtime"
+	"strings"
 
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
@@ -141,7 +142,7 @@ func (r *Router) CallLuaHook(L *lua.LState, ctx context.Context, routeCtx routin
 	if err := L.CallByParam(lua.P{Fn: fn, NRet: 3, Protect: true},
 		value, lua.LString(routeCtx.GetInboundTag()), lua.LNumber(routeCtx.GetSourcePort()),
 		lua.LNumber(routeCtx.GetTargetPort()), lua.LNumber(routeCtx.GetLocalPort()),
-		lua.LString(routeCtx.GetTargetDomain()), lua.LNumber(routeCtx.GetNetwork()),
+		lua.LString(strings.ToLower(routeCtx.GetTargetDomain())), lua.LNumber(routeCtx.GetNetwork()),
 		lua.LString(routeCtx.GetProtocol()), lua.LString(routeCtx.GetUser()),
 		lua.LNumber(routeCtx.GetVlessRoute()), lua.LBool(routeCtx.GetSkipDNSResolve())); err != nil {
 		return "", "", err
diff --git a/app/router/lua_test.go b/app/router/lua_test.go
index 52ccb0e04..518acdb83 100644
--- a/app/router/lua_test.go
+++ b/app/router/lua_test.go
@@ -75,7 +75,7 @@ function HandleRoute(ctx, inboundTag, sourcePort, targetPort, localPort,
     targetDomain, network, protocol, user, vlessRoute, skipDNSResolve, ...)
     assert(select("#", ...) == 0)
     assert(inboundTag == "in" and sourcePort == 1234 and targetPort == 443 and localPort == 5678)
-    assert(targetDomain == "MiXeD.Example." and network == router.NetworkTCP)
+    assert(targetDomain == "mixed.example." and network == router.NetworkTCP)
     assert(protocol == "tls" and user == "user@example.com" and vlessRoute == 4321 and skipDNSResolve)
     assert(ctx.GetNetwork == nil and ctx.Context == nil)
     savedContext = ctx
diff --git a/app/router/script_test.go b/app/router/script_test.go
index 553812cd7..ebc0f5ecc 100644
--- a/app/router/script_test.go
+++ b/app/router/script_test.go
@@ -126,7 +126,7 @@ func TestRouterScriptModules(t *testing.T) {
 	calls := 0
 	d := &luaRouteDNSClient{lookup: func(domain string, option featureDNS.IPOption) ([]net.IP, uint32, error) {
 		calls++
-		if domain != "MiXeD.Example." || !option.IPv4Enable || option.IPv6Enable || !option.FakeEnable {
+		if domain != "mixed.example." || !option.IPv4Enable || option.IPv6Enable || !option.FakeEnable {
 			t.Fatalf("dns.Query arguments = %q, %+v", domain, option)
 		}
 		return ips, 17, nil