diff --git a/Lib/argparse.py b/Lib/argparse.py
index 798766f6c4..96222f0d21 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -539,8 +539,7 @@ class HelpFormatter(object):
     def _format_action_invocation(self, action):
         if not action.option_strings:
             default = self._get_default_metavar_for_positional(action)
-            metavar, = self._metavar_formatter(action, default)(1)
-            return metavar
+            return ', '.join(self._metavar_formatter(action, default)(1))
 
         else:
             parts = []
@@ -709,7 +708,10 @@ def _get_action_name(argument):
     elif argument.option_strings:
         return  '/'.join(argument.option_strings)
     elif argument.metavar not in (None, SUPPRESS):
-        return argument.metavar
+        if isinstance(argument.metavar, tuple):
+            return '(%s)' % ', '.join(argument.metavar)
+        else:
+            return argument.metavar
     elif argument.dest not in (None, SUPPRESS):
         return argument.dest
     else:
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index c0c7cb0594..08833b9177 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -3967,6 +3967,28 @@ class TestHelpTupleMetavar(HelpTestCase):
     version = ''
 
 
+class TestHelpTupleMetavarPositional(HelpTestCase):
+    """Test specifying metavar on a Positional as a tuple"""
+
+    parser_signature = Sig(prog='PROG')
+    argument_signatures = [
+        Sig('foo', help='foo help', nargs=2, metavar=('bar', 'baz'))
+    ]
+    argument_group_signatures = []
+    usage = '''\
+        usage: PROG [-h] bar baz
+        '''
+    help = usage + '''\
+
+        positional arguments:
+          bar, baz    foo help
+
+        optional arguments:
+          -h, --help  show this help message and exit
+        '''
+    version = ''
+
+
 class TestHelpRawText(HelpTestCase):
     """Test the RawTextHelpFormatter"""