diff --git a/mongoengine/base.py b/mongoengine/base.py
index 4523a268..e0e71d31 100644
--- a/mongoengine/base.py
+++ b/mongoengine/base.py
@@ -415,11 +415,8 @@ class BaseDocument(object):
                 self._meta.get('allow_inheritance', True) == False):
             data['_cls'] = self._class_name
             data['_types'] = self._superclasses.keys() + [self._class_name]
-        try:
-            if not data['_id']:
-                del data['_id']
-        except KeyError:
-            pass
+        if data.has_key('_id') and not data['_id']:
+            del data['_id']
         return data
     
     @classmethod