diff --git a/IPython/html/widgets/widget.py b/IPython/html/widgets/widget.py
index bc9696b..85cf02c 100644
--- a/IPython/html/widgets/widget.py
+++ b/IPython/html/widgets/widget.py
@@ -115,7 +115,7 @@ class Widget(LoggingConfigurable):
def _handle_property_changed(self, name, old, new):
- if not self._property_lock:
+ if not self._property_lock and self.comm is not None:
# TODO: Validate properties.
# Send new state to frontend
self.send_state()