diff --git a/scheme.go b/scheme.go
index bfdbe2f..18abbfe 100644
--- a/scheme.go
+++ b/scheme.go
@@ -17,7 +17,7 @@ func (hs *HttpScheme) MarshalJSON() ([]byte, error) {
 	return []byte(hs.String()), nil
 }
 
-const (
+var (
 	SchemeHTTP  HttpScheme = "http"
 	SchemeHTTPS HttpScheme = "https"
 	SchemeWs    HttpScheme = "ws"