diff --git a/Doc/c-api/frame.rst b/Doc/c-api/frame.rst
index 1a52e146a69751..fb17cf7f1da6b2 100644
--- a/Doc/c-api/frame.rst
+++ b/Doc/c-api/frame.rst
@@ -29,6 +29,12 @@ See also :ref:`Reflection <reflection>`.
       Previously, this type was only available after including
       ``<frameobject.h>``.
 
+.. c:function:: PyFrameObject *PyFrame_New(PyThreadState *tstate, PyCodeObject *code, PyObject *globals, PyObject *locals)
+
+   Create a new frame object. This function returns a :term:`strong reference`
+   to the new frame object on success, and returns ``NULL`` with an exception
+   set on failure.
+
 .. c:function:: int PyFrame_Check(PyObject *obj)
 
    Return non-zero if *obj* is a frame object.
@@ -161,6 +167,57 @@ See :pep:`667` for more information.
 
    Return non-zero if *obj* is a frame :func:`locals` proxy.
 
+
+Legacy Local Variable APIs
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These APIs are :term:`soft deprecated`. As of Python 3.13, they do nothing.
+They exist solely for backwards compatibility.
+
+
+.. c:function:: void PyFrame_LocalsToFast(PyFrameObject *f, int clear)
+
+   This function is :term:`soft deprecated` and does nothing.
+
+   Prior to Python 3.13, this function would copy the :attr:`~frame.f_locals`
+   attribute of *f* to the internal "fast" array of local variables, allowing
+   changes in frame objects to be visible to the interpreter. If *clear* was
+   true, this function would process variables that were unset in the locals
+   dictionary.
+
+   .. versionchanged:: 3.13
+      This function now does nothing.
+
+
+.. c:function:: void PyFrame_FastToLocals(PyFrameObject *f)
+
+   This function is :term:`soft deprecated` and does nothing.
+
+   Prior to Python 3.13, this function would copy the internal "fast" array
+   of local variables (which is used by the interpreter) to the
+   :attr:`~frame.f_locals` attribute of *f*, allowing changes in local
+   variables to be visible to frame objects.
+
+   .. versionchanged:: 3.13
+      This function now does nothing.
+
+
+.. c:function:: int PyFrame_FastToLocalsWithError(PyFrameObject *f)
+
+   This function is :term:`soft deprecated` and does nothing.
+
+   Prior to Python 3.13, this function was similar to
+   :c:func:`PyFrame_FastToLocals`, but would return ``0`` on success, and
+   ``-1`` with an exception set on failure.
+
+   .. versionchanged:: 3.13
+      This function now does nothing.
+
+
+.. seealso::
+   :pep:`667`
+
+
 Internal Frames
 ^^^^^^^^^^^^^^^
 
diff --git a/Doc/c-api/type.rst b/Doc/c-api/type.rst
index 5bdbff4e0ad990..479ede70b01f5d 100644
--- a/Doc/c-api/type.rst
+++ b/Doc/c-api/type.rst
@@ -133,6 +133,18 @@ Type Objects
    Type features are denoted by single bit flags.
 
 
+.. c:function:: int PyType_FastSubclass(PyTypeObject *type, int flag)
+
+   Return non-zero if the type object *type* sets the subclass flag *flag*.
+   Subclass flags are denoted by
+   :c:macro:`Py_TPFLAGS_*_SUBCLASS <Py_TPFLAGS_LONG_SUBCLASS>`.
+   This function is used by many ``_Check`` functions for common types.
+
+   .. seealso::
+       :c:func:`PyObject_TypeCheck`, which is used as a slower alternative in
+       ``_Check`` functions for types that don't come with subclass flags.
+
+
 .. c:function:: int PyType_IS_GC(PyTypeObject *o)
 
    Return true if the type object includes support for the cycle detector; this
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index 9d23aea5734ea3..34d19acdf17868 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -1351,8 +1351,8 @@ and :c:data:`PyType_Type` effectively act as defaults.)
    .. c:macro:: Py_TPFLAGS_BASE_EXC_SUBCLASS
    .. c:macro:: Py_TPFLAGS_TYPE_SUBCLASS
 
-      These flags are used by functions such as
-      :c:func:`PyLong_Check` to quickly determine if a type is a subclass
+      Functions such as :c:func:`PyLong_Check` will call :c:func:`PyType_FastSubclass`
+      with one of these flags to quickly determine if a type is a subclass
       of a built-in type; such specific checks are faster than a generic
       check, like :c:func:`PyObject_IsInstance`. Custom types that inherit
       from built-ins should have their :c:member:`~PyTypeObject.tp_flags`
diff --git a/Python/gc_free_threading.c b/Python/gc_free_threading.c
index f39793c3eeb532..b183062eff7952 100644
--- a/Python/gc_free_threading.c
+++ b/Python/gc_free_threading.c
@@ -675,10 +675,11 @@ gc_mark_span_push(gc_span_stack_t *ss, PyObject **start, PyObject **end)
         else {
             ss->capacity *= 2;
         }
-        ss->stack = (gc_span_t *)PyMem_Realloc(ss->stack, ss->capacity * sizeof(gc_span_t));
-        if (ss->stack == NULL) {
+        gc_span_t *new_stack = (gc_span_t *)PyMem_Realloc(ss->stack, ss->capacity * sizeof(gc_span_t));
+        if (new_stack == NULL) {
             return -1;
         }
+        ss->stack = new_stack;
     }
     assert(end > start);
     ss->stack[ss->size].start = start;