diff --git a/Doc/c-api/reflection.rst b/Doc/c-api/reflection.rst
index 21d9878..9207d86 100644
--- a/Doc/c-api/reflection.rst
+++ b/Doc/c-api/reflection.rst
@@ -31,6 +31,17 @@
    See also :c:func:`PyThreadState_GetFrame`.
 
 
+.. c:function:: int PyFrame_GetBack(PyFrameObject *frame)
+
+   Get the *frame* next outer frame.
+
+   Return a strong reference, or ``NULL`` if *frame* has no outer frame.
+
+   *frame* must not be ``NULL``.
+
+   .. versionadded:: 3.9
+
+
 .. c:function:: int PyFrame_GetCode(PyFrameObject *frame)
 
    Get the *frame* code.