diff --git a/IPython/kernel/channels.py b/IPython/kernel/channels.py
index b22cfba..f9b8d93 100644
--- a/IPython/kernel/channels.py
+++ b/IPython/kernel/channels.py
@@ -47,7 +47,7 @@ class HBChannel(Thread):
     _pause = None
     _beating = None
 
-    def __init__(self, context, session, address):
+    def __init__(self, context=None, session=None, address=None):
         """Create the heartbeat monitor thread.
 
         Parameters