diff --git a/mongoengine/base.py b/mongoengine/base.py
index d4412e2a..ec70e5ad 100644
--- a/mongoengine/base.py
+++ b/mongoengine/base.py
@@ -202,9 +202,7 @@ class BaseDocument(object):
         return all_subclasses
 
     def __iter__(self):
-        # Use _data rather than _fields as iterator only looks at names so
-        # values don't need to be converted to Python types
-        return iter(self._data)
+        return iter(self._fields)
 
     def __getitem__(self, name):
         """Dictionary-style field access, return a field's value if present.
diff --git a/mongoengine/queryset.py b/mongoengine/queryset.py
index 7b3f7c6b..95f02891 100644
--- a/mongoengine/queryset.py
+++ b/mongoengine/queryset.py
@@ -132,7 +132,7 @@ class QuerySet(object):
         """Retrieve the object matching the id provided.
         """
         if not isinstance(object_id, pymongo.objectid.ObjectId):
-            object_id = pymongo.objectid.ObjectId(object_id)
+            object_id = pymongo.objectid.ObjectId(str(object_id))
 
         result = self._collection.find_one(object_id)
         if result is not None: