diff --git a/IPython/zmq/kernelmanager.py b/IPython/zmq/kernelmanager.py
index c09dba5..4981f10 100644
--- a/IPython/zmq/kernelmanager.py
+++ b/IPython/zmq/kernelmanager.py
@@ -425,10 +425,10 @@ class KernelManager(HasTraits):
     frontend.
     """
     # The PyZMQ Context to use for communication with the kernel.
-    context = Instance(zmq.Context)
+    context = Instance(zmq.Context,(),{})
 
     # The Session to use for communication with the kernel.
-    session = Instance(Session)
+    session = Instance(Session,(),{})
 
     # The kernel process with which the KernelManager is communicating.
     kernel = Instance(Popen)
@@ -439,22 +439,15 @@ class KernelManager(HasTraits):
     rep_channel_class = Type(RepSocketChannel)
     
     # Protected traits.
-    _xreq_address = TCPAddress
-    _sub_address = TCPAddress
-    _rep_address = TCPAddress
+    xreq_address = TCPAddress((LOCALHOST, 0))
+    sub_address = TCPAddress((LOCALHOST, 0))
+    rep_address = TCPAddress((LOCALHOST, 0))
     _xreq_channel = Any
     _sub_channel = Any
     _rep_channel = Any
 
-    def __init__(self, xreq_address=None, sub_address=None, rep_address=None,
-                 context=None, session=None):
-        super(KernelManager, self).__init__()
-        self._xreq_address = (LOCALHOST, 0) if xreq_address is None else xreq_address
-        self._sub_address = (LOCALHOST, 0) if sub_address is None else sub_address
-        self._rep_address = (LOCALHOST, 0) if rep_address is None else rep_address
-        self.context = zmq.Context() if context is None else context
-        self.session = Session() if session is None else session
-        super(KernelManager, self).__init__()
+    def __init__(self, **kwargs):
+        super(KernelManager, self).__init__(**kwargs)
 
     #---------------------------------  -----------------------------------------
     # Channel management methods:
@@ -507,9 +500,9 @@ class KernelManager(HasTraits):
 
         self.kernel, xrep, pub, req = launch_kernel(
             xrep_port=xreq[1], pub_port=sub[1], req_port=rep[1])
-        self._xreq_address = (LOCALHOST, xrep)
-        self._sub_address = (LOCALHOST, pub)
-        self._rep_address = (LOCALHOST, req)
+        self.xreq_address = (LOCALHOST, xrep)
+        self.sub_address = (LOCALHOST, pub)
+        self.rep_address = (LOCALHOST, req)
 
     @property
     def has_kernel(self):
@@ -576,16 +569,3 @@ class KernelManager(HasTraits):
                                                        self.session,
                                                        self.rep_address)
         return self._rep_channel
-
-    @property
-    def xreq_address(self):
-        return self._xreq_address
-
-    @property
-    def sub_address(self):
-        return self._sub_address
-
-    @property
-    def rep_address(self):
-        return self._rep_address
-