diff --git a/ipykernel/inprocess/manager.py b/ipykernel/inprocess/manager.py
index f46d89d53..ccdaccadf 100644
--- a/ipykernel/inprocess/manager.py
+++ b/ipykernel/inprocess/manager.py
@@ -46,6 +46,7 @@ def start_kernel(self, **kwds):
         self.kernel = InProcessKernel(parent=self, session=self.session)
 
     def shutdown_kernel(self):
+        self.kernel.iopub_thread.stop()
         self._kill_kernel()
 
     def restart_kernel(self, now=False, **kwds):