diff --git a/IPython/html/widgets/widget.py b/IPython/html/widgets/widget.py
index eb7f50b..11d8147 100644
--- a/IPython/html/widgets/widget.py
+++ b/IPython/html/widgets/widget.py
@@ -100,7 +100,7 @@ class BaseWidget(LoggingConfigurable):
     
     @property
     def model_id(self):
-        return self._comm.comm_id
+        return self.comm.comm_id
 
     # Event handlers
     def _handle_msg(self, msg):