diff --git a/Doc/library/string.rst b/Doc/library/string.rst
index a0977b6..03eaf3b 100644
--- a/Doc/library/string.rst
+++ b/Doc/library/string.rst
@@ -95,9 +95,9 @@
       an arbitrary set of positional and keyword arguments.
       It is just a wrapper that calls :meth:`vformat`.
 
-      .. deprecated:: 3.5
-         Passing a format string as keyword argument *format_string* has been
-         deprecated.
+      .. versionchanged:: 3.7
+         A format string argument is now :ref:`positional-only
+         <positional-only_parameter>`.
 
    .. method:: vformat(format_string, args, kwargs)
 
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index a2e6422..c4814e2 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -147,3 +147,9 @@
 that may require changes to your code.
 
 
+Changes in the Python API
+-------------------------
+
+* A format string argument for :meth:`string.Formatter.format`
+  is now :ref:`positional-only <positional-only_parameter>`.
+  (Contributed by Serhiy Storchaka in :issue:`29193`.)