diff --git a/Doc/library/decimal.rst b/Doc/library/decimal.rst
index 3fa006bec22..4a2b2d0a9bf 100644
--- a/Doc/library/decimal.rst
+++ b/Doc/library/decimal.rst
@@ -737,6 +737,11 @@ Decimal objects
       resulting exponent is greater than :attr:`Emax` or less than
       :attr:`Etiny`.
 
+      .. deprecated:: 3.3
+         *watchexp* is an implementation detail from the pure Python version
+         and is not present in the C version. It will be removed in version
+         3.4, where it defaults to ``True``.
+
    .. method:: radix()
 
       Return ``Decimal(10)``, the radix (base) in which the :class:`Decimal`
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index 27bf12dd9f3..e019ea7f700 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -1190,6 +1190,10 @@ API changes
   changed to match the order displayed by :func:`repr`.
 
 
+* The ``watchexp`` parameter in the :meth:`~decimal.Decimal.quantize` method
+  is deprecated.
+
+
 ftplib
 ------
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 9a9a587a988..dad1622c44d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -51,6 +51,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #10650: Deprecate the watchexp parameter of the Decimal.quantize()
+  method.
+
 - Issue #15785: Modify window.get_wch() API of the curses module: return
   a character for most keys, and an integer for special keys, instead of
   always returning an integer. So it is now possible to distinguish special