diff --git a/ipykernel/inprocess/ipkernel.py b/ipykernel/inprocess/ipkernel.py
index 7ed47443b..e61af4277 100644
--- a/ipykernel/inprocess/ipkernel.py
+++ b/ipykernel/inprocess/ipkernel.py
@@ -56,7 +56,7 @@ class InProcessKernel(IPythonKernel):
 
     @default("iopub_thread")
     def _default_iopub_thread(self):
-        thread = IOPubThread(self._underlying_iopub_socket, self.session)
+        thread = IOPubThread(self._underlying_iopub_socket, session=self.session)
         thread.start()
         return thread
 
diff --git a/ipykernel/iostream.py b/ipykernel/iostream.py
index a426139ed..33213d167 100644
--- a/ipykernel/iostream.py
+++ b/ipykernel/iostream.py
@@ -47,7 +47,7 @@ class IOPubThread:
     whose IO is always run in a thread.
     """
 
-    def __init__(self, socket, session=None, pipe=False):
+    def __init__(self, socket, pipe=False, session=False):
         """Create IOPub thread
 
         Parameters
@@ -518,7 +518,7 @@ def __init__(
                 DeprecationWarning,
                 stacklevel=2,
             )
-            pub_thread = IOPubThread(pub_thread, self.session)
+            pub_thread = IOPubThread(pub_thread, session=self.session)
             pub_thread.start()
         self.pub_thread = pub_thread
         self.name = name
diff --git a/ipykernel/kernelapp.py b/ipykernel/kernelapp.py
index a450d6ca7..b2f614ea9 100644
--- a/ipykernel/kernelapp.py
+++ b/ipykernel/kernelapp.py
@@ -382,7 +382,7 @@ def init_iopub(self, context):
         self.iopub_port = self._bind_socket(self.iopub_socket, self.iopub_port)
         self.log.debug("iopub PUB Channel on port: %i", self.iopub_port)
         self.configure_tornado_logger()
-        self.iopub_thread = IOPubThread(self.iopub_socket, self.session, pipe=True)
+        self.iopub_thread = IOPubThread(self.iopub_socket, pipe=True, session=self.session)
         self.iopub_thread.start()
         # backward-compat: wrap iopub socket API in background thread
         self.iopub_socket = self.iopub_thread.background_socket
diff --git a/tests/test_io.py b/tests/test_io.py
index da1000f4e..217680a4f 100644
--- a/tests/test_io.py
+++ b/tests/test_io.py
@@ -28,7 +28,7 @@ def ctx():
 def iopub_thread(ctx):
     session = Session()
     with ctx.socket(zmq.PUB) as pub:
-        thread = IOPubThread(pub, session)
+        thread = IOPubThread(pub, session=session)
         thread.start()
 
         yield thread
@@ -156,7 +156,7 @@ def subprocess_test_echo_watch():
     # use PUSH socket to avoid subscription issues
     with zmq.Context() as ctx, ctx.socket(zmq.PUSH) as pub:
         pub.connect(os.environ["IOPUB_URL"])
-        iopub_thread = IOPubThread(pub, session)
+        iopub_thread = IOPubThread(pub, session=session)
         iopub_thread.start()
         stdout_fd = sys.stdout.fileno()
         sys.stdout.flush()