diff --git a/ipykernel/inprocess/client.py b/ipykernel/inprocess/client.py
index 2e562f040..c926fd159 100644
--- a/ipykernel/inprocess/client.py
+++ b/ipykernel/inprocess/client.py
@@ -172,6 +172,9 @@ def _dispatch_to_kernel(self, msg):
         idents, reply_msg = self.session.recv(stream, copy=False)
         self.shell_channel.call_handlers_later(reply_msg)
 
+    def flush(self):
+        """no-op to comply with stream API"""
+
 
 #-----------------------------------------------------------------------------
 # ABC Registration