Index: Lib/test/test_subprocess.py
===================================================================
--- Lib/test/test_subprocess.py	(révision 78635)
+++ Lib/test/test_subprocess.py	(copie de travail)
@@ -522,7 +522,15 @@
             if c.exception.errno != 2:  # ignore "no such file"
                 raise c.exception
 
+    def test_bytes(self):
+        # mix str and bytes
+        exitcode = subprocess.call([sys.executable, "-c", b"pass"])
+        self.assertEqual(exitcode, 0)
 
+        exitcode = subprocess.call('"%s" -c pass' % sys.executable, shell=True)
+        self.assertEqual(exitcode, 0)
+
+
 # context manager
 class _SuppressCoreFiles(object):
     """Try to prevent core files from being created."""
Index: Lib/subprocess.py
===================================================================
--- Lib/subprocess.py	(révision 78635)
+++ Lib/subprocess.py	(copie de travail)
@@ -1037,7 +1037,7 @@
                            errread, errwrite):
             """Execute program (POSIX version)"""
 
-            if isinstance(args, str):
+            if isinstance(args, (str, bytes)):
                 args = [args]
             else:
                 args = list(args)