diff --git a/include/ws_protocols/rest_encoder.php b/include/ws_protocols/rest_encoder.php
index 889ed37e7..b7b32ae96 100644
--- a/include/ws_protocols/rest_encoder.php
+++ b/include/ws_protocols/rest_encoder.php
@@ -140,6 +140,7 @@ class PwgXmlWriter
 
 class PwgRestEncoder extends PwgResponseEncoder
 {
+  private $_writer;
   function encodeResponse($response)
   {
     if ($response instanceof PwgError)