diff --git a/main.go b/main.go
index e9f66058..d41450b6 100644
--- a/main.go
+++ b/main.go
@@ -21,7 +21,6 @@ import (
 )
 
 var (
-	flagset            map[string]bool
 	version            bool
 	testConfig         bool
 	geodataMode        bool
@@ -33,20 +32,15 @@ var (
 )
 
 func init() {
-	flag.StringVar(&homeDir, "d", "", "set configuration directory")
-	flag.StringVar(&configFile, "f", "", "specify configuration file")
-	flag.StringVar(&externalUI, "ext-ui", "", "override external ui directory")
-	flag.StringVar(&externalController, "ext-ctl", "", "override external controller address")
-	flag.StringVar(&secret, "secret", "", "override secret for RESTful API")
+	flag.StringVar(&homeDir, "d", os.Getenv("CLASH_HOME_DIR"), "set configuration directory")
+	flag.StringVar(&configFile, "f", os.Getenv("CLASH_CONFIG_FILE"), "specify configuration file")
+	flag.StringVar(&externalUI, "ext-ui", os.Getenv("CLASH_OVERRIDE_EXTERNAL_UI_DIR"), "override external ui directory")
+	flag.StringVar(&externalController, "ext-ctl", os.Getenv("CLASH_OVERRIDE_EXTERNAL_CONTROLLER"), "override external controller address")
+	flag.StringVar(&secret, "secret", os.Getenv("CLASH_OVERRIDE_SECRET"), "override secret for RESTful API")
 	flag.BoolVar(&geodataMode, "m", false, "set geodata mode")
 	flag.BoolVar(&version, "v", false, "show current version of clash")
 	flag.BoolVar(&testConfig, "t", false, "test configuration and exit")
 	flag.Parse()
-
-	flagset = map[string]bool{}
-	flag.Visit(func(f *flag.Flag) {
-		flagset[f.Name] = true
-	})
 }
 
 func main() {
@@ -99,13 +93,13 @@ func main() {
 	}
 
 	var options []hub.Option
-	if flagset["ext-ui"] {
+	if externalUI != "" {
 		options = append(options, hub.WithExternalUI(externalUI))
 	}
-	if flagset["ext-ctl"] {
+	if externalController != "" {
 		options = append(options, hub.WithExternalController(externalController))
 	}
-	if flagset["secret"] {
+	if secret != "" {
 		options = append(options, hub.WithSecret(secret))
 	}