diff --git a/proxy/socks/client_config_json.go b/proxy/socks/client_config_json.go
index 87e47afc..fd31a366 100644
--- a/proxy/socks/client_config_json.go
+++ b/proxy/socks/client_config_json.go
@@ -1,3 +1,5 @@
+// +build json
+
 package socks
 
 import (