diff --git a/lib/mongoose/document.js b/lib/mongoose/document.js
index edadf075136..8bb5bd73d2d 100644
--- a/lib/mongoose/document.js
+++ b/lib/mongoose/document.js
@@ -451,14 +451,24 @@ Document.prototype.__defineGetter__('modified', function () {
  */
 
 function compile (tree, proto, prefix) {
-  for (var i in tree)
-    define(i, ((tree[i].constructor == Object
-               && Object.keys(tree[i]).length)
-               && (!tree[i].type || tree[i].__nested)
-               ? tree[i]
+  var keys = Object.keys(tree)
+    , i = keys.length
+    , limb
+    , key;
+
+  while (i--) {
+    key = keys[i];
+    limb = tree[key];
+
+    define(key
+        , ((limb.constructor == Object
+               && Object.keys(limb).length)
+               && (!limb.type || limb.type.type)
+               ? limb
                : null)
-            , proto
-            , prefix);
+        , proto
+        , prefix);
+  }
 };
 
 function define (prop, subprops, prototype, prefix) {