diff --git a/notebook/services/kernels/kernelmanager.py b/notebook/services/kernels/kernelmanager.py
index cc739afec..6297eb5ad 100644
--- a/notebook/services/kernels/kernelmanager.py
+++ b/notebook/services/kernels/kernelmanager.py
@@ -115,7 +115,7 @@ class MappingKernelManager(MultiKernelManager):
         
         def finish():
             """Common cleanup when restart finishes/fails for any reason."""
-            if not channel.closed:
+            if not channel.closed():
                 channel.close()
             loop.remove_timeout(timeout)
             kernel.remove_restart_callback(on_restart_failed, 'dead')
diff --git a/notebook/tests/launchnotebook.py b/notebook/tests/launchnotebook.py
index 7e24ee2da..2537a5b9a 100644
--- a/notebook/tests/launchnotebook.py
+++ b/notebook/tests/launchnotebook.py
@@ -18,6 +18,7 @@ except ImportError:
     from mock import patch #py2
 
 from tornado.ioloop import IOLoop
+import zmq
 
 import jupyter_core.paths
 from ..notebookapp import NotebookApp
@@ -132,6 +133,16 @@ class NotebookTestBase(TestCase):
         cls.notebook_dir.cleanup()
         cls.env_patch.stop()
         cls.path_patch.stop()
+        # cleanup global zmq Context, to ensure we aren't leaving dangling sockets
+        def cleanup_zmq():
+            zmq.Context.instance().term()
+        t = Thread(target=cleanup_zmq)
+        t.daemon = True
+        t.start()
+        t.join(5) # give it a few seconds to clean up (this should be immediate)
+        # if term never returned, there's zmq stuff still open somewhere, so shout about it.
+        if t.is_alive():
+            raise RuntimeError("Failed to teardown zmq Context, open sockets likely left lying around.")
 
     @classmethod
     def base_url(cls):