diff --git a/Lib/argparse.py b/Lib/argparse.py
index 2fb1da59f942cf..525c8720005479 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -547,7 +547,7 @@ def _format_action(self, action):
     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)
+            metavar = self._metavar_formatter(action, default)(1)[0]
             return metavar
 
         else:
diff --git a/Misc/NEWS.d/next/Library/2020-12-03-00-40-12.bpo-42547.O2BJhp.rst b/Misc/NEWS.d/next/Library/2020-12-03-00-40-12.bpo-42547.O2BJhp.rst
new file mode 100644
index 00000000000000..1266d0d670f4ea
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-12-03-00-40-12.bpo-42547.O2BJhp.rst
@@ -0,0 +1 @@
+argparse: fixed `add_argument(metavar=<tuple>, nargs='+')` for positional arguments