diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a6c216b46..3a3d38f35 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -38,6 +38,7 @@ jobs:
       - name: Install the Python dependencies
         run: |
           pip install .[test] codecov
+          pip install https://github.com/davidbrochart/jupyter_client/archive/async_stream.zip
 
       - name: Install matplotlib
         if: ${{ !startsWith(matrix.os, 'macos') && !startsWith(matrix.python-version, 'pypy') }}
diff --git a/.github/workflows/downstream.yml b/.github/workflows/downstream.yml
index 061299943..181cfd9f5 100644
--- a/.github/workflows/downstream.yml
+++ b/.github/workflows/downstream.yml
@@ -68,4 +68,5 @@ jobs:
           git clone https://github.com/jupyter/jupyter_kernel_test.git
           cd jupyter_kernel_test
           pip install -e ".[test]"
+          pip install https://github.com/davidbrochart/jupyter_client/archive/async_stream.zip
           python test_ipykernel.py
diff --git a/ipykernel/iostream.py b/ipykernel/iostream.py
index 38b6815dc..2b19d7fcc 100644
--- a/ipykernel/iostream.py
+++ b/ipykernel/iostream.py
@@ -190,6 +190,7 @@ def stop(self):
         # so after thread.join, this should be safe
         for event_pipe in self._event_pipes:
             event_pipe.close()
+        self._event_puller.socket.close()
 
     def close(self):
         if self.closed:
diff --git a/ipykernel/tests/test_io.py b/ipykernel/tests/test_io.py
index 7e2950976..89cfd06b0 100644
--- a/ipykernel/tests/test_io.py
+++ b/ipykernel/tests/test_io.py
@@ -4,6 +4,7 @@
 
 import pytest
 import zmq
+import zmq.asyncio
 from jupyter_client.session import Session
 
 from ipykernel.iostream import IOPubThread, OutStream
@@ -12,7 +13,7 @@
 def test_io_api():
     """Test that wrapped stdout has the same API as a normal TextIO object"""
     session = Session()
-    ctx = zmq.Context()
+    ctx = zmq.asyncio.Context()
     pub = ctx.socket(zmq.PUB)
     thread = IOPubThread(pub)
     thread.start()
diff --git a/ipykernel/zmqstream.py b/ipykernel/zmqstream.py
index 158b94d09..2b0bfcd33 100644
--- a/ipykernel/zmqstream.py
+++ b/ipykernel/zmqstream.py
@@ -27,5 +27,5 @@ async def recv_task(self, callback, copy):
     def send_multipart(self, msg_list, flags=0, copy=True, track=False, **kwargs):
         return self.socket.send_multipart(msg_list, copy=copy)
 
-    def flush(self, flag=None, limit = None):
+    def flush(self, flag=None, limit=None):
         pass