diff --git a/response.go b/response.go
index feda869..b33b9c8 100644
--- a/response.go
+++ b/response.go
@@ -1,53 +1,53 @@
 package impart
 
 import (
 	"encoding/json"
 	"net/http"
 	"strconv"
 )
 
 type (
-	// envelope contains metadata and optional data for a response object.
-	envelope struct {
+	// Envelope contains metadata and optional data for a response object.
+	Envelope struct {
 		Code         int         `json:"code"`
 		ErrorType    string      `json:"error_type,omitempty"`
 		ErrorMessage string      `json:"error_msg,omitempty"`
 		Data         interface{} `json:"data,omitempty"`
 	}
 )
 
 func writeBody(w http.ResponseWriter, body []byte, status int, contentType string) error {
 	w.Header().Set("Content-Type", contentType+"; charset=UTF-8")
 	w.Header().Set("Content-Length", strconv.Itoa(len(body)))
 	w.WriteHeader(status)
 	_, err := w.Write(body)
 	return err
 }
 
 func renderJSON(w http.ResponseWriter, value interface{}, status int) error {
 	body, err := json.Marshal(value)
 	if err != nil {
 		return err
 	}
 	return writeBody(w, body, status, "application/json")
 }
 
 func renderString(w http.ResponseWriter, status int, msg string) error {
 	return writeBody(w, []byte(msg), status, "text/plain")
 }
 
 func WriteSuccess(w http.ResponseWriter, data interface{}, status int) error {
-	env := &envelope{
+	env := &Envelope{
 		Code: status,
 		Data: data,
 	}
 	return renderJSON(w, env, status)
 }
 
 func WriteError(w http.ResponseWriter, e HTTPError) error {
-	env := &envelope{
+	env := &Envelope{
 		Code:         e.Status,
 		ErrorMessage: e.Message,
 	}
 	return renderJSON(w, env, e.Status)
 }