diff --git a/ipykernel/kernelapp.py b/ipykernel/kernelapp.py
index 8374a38c..c0c0628a 100644
--- a/ipykernel/kernelapp.py
+++ b/ipykernel/kernelapp.py
@@ -427,7 +427,7 @@ def close(self):
         if self.debug_shell_socket and not self.debug_shell_socket.closed:
             self.debug_shell_socket.close()
 
-        for channel in ("shell", "control", "stdin", "iopub"):
+        for channel in ("shell", "control", "stdin"):
             self.log.debug("Closing %s channel", channel)
             socket = getattr(self, channel + "_socket", None)
             if socket and not socket.closed: