diff --git a/lib/Connection.js b/lib/Connection.js
index 6f5fdb7..9f10dc9 100644
--- a/lib/Connection.js
+++ b/lib/Connection.js
@@ -1293,9 +1293,9 @@ Connection.prototype._resUntagged = function(info) {
         parent: null
       };
 
-      for (var i = 0, len = SPECIAL_USE_ATTRIBUTES.length; i < len; ++i)
-        if (box['attribs'].indexOf(SPECIAL_USE_ATTRIBUTES[i]) > -1)
-          box['special_use_attrib'] = SPECIAL_USE_ATTRIBUTES[i];
+      for (i = 0, len = SPECIAL_USE_ATTRIBUTES.length; i < len; ++i)
+        if (box.attribs.indexOf(SPECIAL_USE_ATTRIBUTES[i]) > -1)
+          box.special_use_attrib = SPECIAL_USE_ATTRIBUTES[i];
 
       var name = info.text.name,
           curChildren = this._curReq.cbargs[0];