diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index aced876..ba2844d 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -373,7 +373,9 @@
         # matches *expected_cwd*.
         p = subprocess.Popen([python_arg, "-c",
                               "import os, sys; "
-                              "sys.stdout.write(os.getcwd()); "
+                              "buf = sys.stdout.buffer; "
+                              "buf.write(os.getcwd().encode()); "
+                              "buf.flush(); "
                               "sys.exit(47)"],
                               stdout=subprocess.PIPE,
                               **kwargs)
@@ -382,7 +384,7 @@
         self.assertEqual(47, p.returncode)
         normcase = os.path.normcase
         self.assertEqual(normcase(expected_cwd),
-                         normcase(p.stdout.read().decode("utf-8")))
+                         normcase(p.stdout.read().decode()))
 
     def test_cwd(self):
         # Check that cwd changes the cwd for the child process.