Issue 21479: Fix markup for the TarFile.open() classmethod.
diff --git a/Doc/library/tarfile.rst b/Doc/library/tarfile.rst
index 99a9f2b..1c6b67c 100644
--- a/Doc/library/tarfile.rst
+++ b/Doc/library/tarfile.rst
@@ -305,7 +305,7 @@
    .. versionadded:: 2.6
 
 
-.. method:: TarFile.open(...)
+.. classmethod:: TarFile.open(...)
 
    Alternative constructor. The :func:`tarfile.open` function is actually a
    shortcut to this classmethod.