diff --git a/cheroot/connections.py b/cheroot/connections.py
index 6bba727479..7debcbfd18 100644
--- a/cheroot/connections.py
+++ b/cheroot/connections.py
@@ -216,7 +216,8 @@ def _run(self, expiration_interval):
                 if conn is self.server:
                     # New connection
                     new_conn = self._from_server_socket(self.server.socket)
-                    self.server.process_conn(new_conn)
+                    if new_conn is not None:
+                        self.server.process_conn(new_conn)
                 else:
                     # unregister connection from the selector until the server
                     # has read from it and returned it via put()