diff --git a/config/config.go b/config/config.go
index ef3f20f..72ee15f 100644
--- a/config/config.go
+++ b/config/config.go
@@ -325,51 +325,12 @@ func BuildConfig(configOpt ConfigOptions, input option.Options) option.Options {
 	var outbounds []option.Outbound
 	var tags []string
 	for _, out := range input.Outbounds {
-		jsonData, err := out.MarshalJSON()
+		outbound, serverDomain, err := patchOutbound(out, configOpt)
 		if err == nil {
-			var obj map[string]interface{}
-			err = json.Unmarshal(jsonData, &obj)
-			if err == nil {
-				if value, ok := obj["server"]; ok {
-					server := value.(string)
-					if server != "" && net.ParseIP(server) == nil {
-						directDNSDomains = append(directDNSDomains, fmt.Sprintf("full:%s", server))
-					}
-				}
-
-				if !(out.Type == C.TypeSelector || out.Type == C.TypeURLTest || out.Type == C.TypeBlock || out.Type == C.TypeDNS) {
-					if configOpt.EnableFragment {
-						tlsFragment := option.TLSFragmentOptions{
-							Enabled: configOpt.TLSTricks.EnableFragment,
-							Size:    configOpt.TLSTricks.FragmentSize,
-							Sleep:   configOpt.TLSTricks.FragmentSleep,
-						}
-						obj["tls_fragment"] = tlsFragment
-					}
-
-					if value, ok := obj["tls"]; ok {
-						tlsTricks := option.TLSTricksOptions{
-							MixedCaseSNI: configOpt.TLSTricks.EnableMixedSNICase,
-						}
-
-						if configOpt.TLSTricks.EnablePadding {
-							tlsTricks.PaddingMode = "random"
-							tlsTricks.PaddingSize = configOpt.TLSTricks.PaddingSize
-						}
-						if tlsTricks.MixedCaseSNI || tlsTricks.PaddingMode != "" {
-							value.(map[string]interface{})["tls_tricks"] = tlsTricks
-						}
-					}
-				}
-
-				modifiedJson, err := json.Marshal(obj)
-				if err == nil {
-					err = out.UnmarshalJSON(modifiedJson)
-					if err != nil {
-						fmt.Println("error: ", out.Tag, out.Type, err)
-					}
-				}
+			if serverDomain != "" {
+				directDNSDomains = append(directDNSDomains, serverDomain)
 			}
+			out = *outbound
 		}
 
 		switch out.Type {
diff --git a/config/outbound.go b/config/outbound.go
new file mode 100644
index 0000000..8c1dc77
--- /dev/null
+++ b/config/outbound.go
@@ -0,0 +1,78 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/option"
+)
+
+func patchOutbound(base option.Outbound, configOpt ConfigOptions) (*option.Outbound, string, error) {
+	var serverDomain string
+	var outbound option.Outbound
+
+	formatErr := func(err error) error {
+		return fmt.Errorf("error patching outbound[%s][%s]: %w", base.Tag, base.Type, err)
+	}
+
+	jsonData, err := base.MarshalJSON()
+	if err != nil {
+		return nil, "", formatErr(err)
+	}
+
+	var obj map[string]interface{}
+	err = json.Unmarshal(jsonData, &obj)
+	if err != nil {
+		return nil, "", formatErr(err)
+	}
+
+	if server, ok := obj["server"].(string); ok {
+		if server != "" && net.ParseIP(server) == nil {
+			serverDomain = fmt.Sprintf("full:%s", server)
+		}
+	}
+
+	if !(base.Type == C.TypeSelector || base.Type == C.TypeURLTest || base.Type == C.TypeBlock || base.Type == C.TypeDNS) {
+		if configOpt.EnableFragment {
+			tlsFragment := option.TLSFragmentOptions{
+				Enabled: configOpt.TLSTricks.EnableFragment,
+				Size:    configOpt.TLSTricks.FragmentSize,
+				Sleep:   configOpt.TLSTricks.FragmentSleep,
+			}
+			obj["tls_fragment"] = tlsFragment
+		} else {
+			obj["tls_fragment"] = nil
+		}
+
+		if tls, ok := obj["tls"].(map[string]interface{}); ok {
+			tlsTricks := option.TLSTricksOptions{
+				MixedCaseSNI: configOpt.TLSTricks.EnableMixedSNICase,
+			}
+
+			if configOpt.TLSTricks.EnablePadding {
+				tlsTricks.PaddingMode = "random"
+				tlsTricks.PaddingSize = configOpt.TLSTricks.PaddingSize
+			}
+
+			if tlsTricks.MixedCaseSNI || tlsTricks.PaddingMode != "" {
+				tls["tls_tricks"] = tlsTricks
+			} else {
+				tls["tls_tricks"] = nil
+			}
+		}
+	}
+
+	modifiedJson, err := json.Marshal(obj)
+	if err != nil {
+		return nil, "", formatErr(err)
+	}
+
+	err = outbound.UnmarshalJSON(modifiedJson)
+	if err != nil {
+		return nil, "", formatErr(err)
+	}
+
+	return &outbound, serverDomain, nil
+}