diff --git a/constant/adapters.go b/constant/adapters.go
index 09c437f5..105a7904 100644
--- a/constant/adapters.go
+++ b/constant/adapters.go
@@ -185,6 +185,8 @@ func (at AdapterType) String() string {
 		return "Compatible"
 	case Pass:
 		return "Pass"
+	case Dns:
+		return "Dns"
 	case Shadowsocks:
 		return "Shadowsocks"
 	case ShadowsocksR: