diff --git a/httpcli.go b/httpcli.go
index ff8e88f..fa9c00d 100644
--- a/httpcli.go
+++ b/httpcli.go
@@ -13,6 +13,10 @@ const (
 	HTTP_OPT_SET_PROXY  = iota
 )
 
+const (
+	HTTP_HEADER_JSON = "application/json"
+)
+
 func internalSetOpt(client *http.Client, request *http.Request, opt int32,
 	key string, val string) {
 	switch opt {