diff --git a/mercurial/archival.py b/mercurial/archival.py
--- a/mercurial/archival.py
+++ b/mercurial/archival.py
@@ -163,16 +163,7 @@ class tarit:
                     mtime=mtime,
                 )
                 self.fileobj = gzfileobj
-                return (
-                    # taropen() wants Literal['a', 'r', 'w', 'x'] for the mode,
-                    # but Literal[] is only available in 3.8+ without the
-                    # typing_extensions backport.
-                    # pytype: disable=wrong-arg-types
-                    tarfile.TarFile.taropen(  # pytype: disable=attribute-error
-                        name, pycompat.sysstr(mode), gzfileobj
-                    )
-                    # pytype: enable=wrong-arg-types
-                )
+                return tarfile.TarFile.taropen(name, "w", gzfileobj)
             else:
                 try:
                     return tarfile.open(