diff --git a/Lib/test/test_pty.py b/Lib/test/test_pty.py
index f283e19..ee9b589 100644
--- a/Lib/test/test_pty.py
+++ b/Lib/test/test_pty.py
@@ -10,6 +10,7 @@ import sys
 import select
 import signal
 import socket
+import io
 import unittest
 
 TEST_STRING_1 = b"I wish to buy a fish license.\n"
@@ -92,17 +93,18 @@ class PtyTest(unittest.TestCase):
             # Restore the original flags.
             os.set_blocking(master_fd, blocking)
 
-        debug("Writing to slave_fd")
-        os.write(slave_fd, TEST_STRING_1)
-        s1 = os.read(master_fd, 1024)
-        self.assertEqual(b'I wish to buy a fish license.\n',
-                         normalize_output(s1))
-
-        debug("Writing chunked output")
-        os.write(slave_fd, TEST_STRING_2[:5])
-        os.write(slave_fd, TEST_STRING_2[5:])
-        s2 = os.read(master_fd, 1024)
-        self.assertEqual(b'For my pet fish, Eric.\n', normalize_output(s2))
+        with io.FileIO(master_fd, mode='rb', closefd=False) as master:
+            debug("Writing to slave_fd")
+            os.write(slave_fd, TEST_STRING_1)
+            s1 = master.readline()
+            self.assertEqual(b'I wish to buy a fish license.\n',
+                             normalize_output(s1))
+
+            debug("Writing chunked output")
+            os.write(slave_fd, TEST_STRING_2[:5])
+            os.write(slave_fd, TEST_STRING_2[5:])
+            s2 = master.readline()
+            self.assertEqual(b'For my pet fish, Eric.\n', normalize_output(s2))
 
         os.close(slave_fd)
         os.close(master_fd)