diff --git a/adapter/outboundgroup/fallback.go b/adapter/outboundgroup/fallback.go
index 15486111..2e754133 100644
--- a/adapter/outboundgroup/fallback.go
+++ b/adapter/outboundgroup/fallback.go
@@ -97,7 +97,7 @@ func (f *Fallback) SupportUDP() bool {
 
 // MarshalJSON implements C.ProxyAdapter
 func (f *Fallback) MarshalJSON() ([]byte, error) {
-	var all []string
+	all := []string{}
 	for _, proxy := range f.proxies(false) {
 		all = append(all, proxy.Name())
 	}
diff --git a/adapter/outboundgroup/loadbalance.go b/adapter/outboundgroup/loadbalance.go
index 0a4dce9c..3a326187 100644
--- a/adapter/outboundgroup/loadbalance.go
+++ b/adapter/outboundgroup/loadbalance.go
@@ -150,7 +150,7 @@ func (lb *LoadBalance) proxies(touch bool) []C.Proxy {
 
 // MarshalJSON implements C.ProxyAdapter
 func (lb *LoadBalance) MarshalJSON() ([]byte, error) {
-	var all []string
+	all := []string{}
 	for _, proxy := range lb.proxies(false) {
 		all = append(all, proxy.Name())
 	}
diff --git a/adapter/outboundgroup/relay.go b/adapter/outboundgroup/relay.go
index f75bd336..d9b29637 100644
--- a/adapter/outboundgroup/relay.go
+++ b/adapter/outboundgroup/relay.go
@@ -69,7 +69,7 @@ func (r *Relay) DialContext(ctx context.Context, metadata *C.Metadata, opts ...d
 
 // MarshalJSON implements C.ProxyAdapter
 func (r *Relay) MarshalJSON() ([]byte, error) {
-	var all []string
+	all := []string{}
 	for _, proxy := range r.rawProxies(false) {
 		all = append(all, proxy.Name())
 	}
diff --git a/adapter/outboundgroup/selector.go b/adapter/outboundgroup/selector.go
index 32a8f247..d3b58b3f 100644
--- a/adapter/outboundgroup/selector.go
+++ b/adapter/outboundgroup/selector.go
@@ -50,7 +50,7 @@ func (s *Selector) SupportUDP() bool {
 
 // MarshalJSON implements C.ProxyAdapter
 func (s *Selector) MarshalJSON() ([]byte, error) {
-	var all []string
+	all := []string{}
 	for _, proxy := range getProvidersProxies(s.providers, false, s.filter) {
 		all = append(all, proxy.Name())
 	}
diff --git a/adapter/outboundgroup/urltest.go b/adapter/outboundgroup/urltest.go
index 60b28273..98269e6a 100644
--- a/adapter/outboundgroup/urltest.go
+++ b/adapter/outboundgroup/urltest.go
@@ -123,7 +123,7 @@ func (u *URLTest) SupportUDP() bool {
 
 // MarshalJSON implements C.ProxyAdapter
 func (u *URLTest) MarshalJSON() ([]byte, error) {
-	var all []string
+	all := []string{}
 	for _, proxy := range u.proxies(false) {
 		all = append(all, proxy.Name())
 	}