diff --git a/Lib/test/test_termios.py b/Lib/test/test_termios.py
index cbc922bb3e31ca..91c92c3f2e6ec2 100644
--- a/Lib/test/test_termios.py
+++ b/Lib/test/test_termios.py
@@ -169,6 +169,9 @@ def test_tcflow(self):
         termios.tcflow(self.fd, termios.TCOON)
         termios.tcflow(self.fd, termios.TCIOFF)
         termios.tcflow(self.fd, termios.TCION)
+        # Discard the transmitted STOP and START characters,
+        # otherwise closing the pseudo-terminal can block.
+        termios.tcflush(self.fd, termios.TCOFLUSH)
 
     def test_tcflow_errors(self):
         self.assertRaisesTermiosError(errno.EINVAL, termios.tcflow, self.fd, -1)