diff --git a/Include/genobject.h b/Include/genobject.h
index 25f6c33d1cc..ed451baf3cb 100644
--- a/Include/genobject.h
+++ b/Include/genobject.h
@@ -34,7 +34,7 @@ PyAPI_DATA(PyTypeObject) PyGen_Type;
 
 PyAPI_FUNC(PyObject *) PyGen_New(struct _frame *);
 PyAPI_FUNC(int) PyGen_NeedsFinalizing(PyGenObject *);
-PyAPI_FUNC(int) PyGen_FetchStopIterationValue(PyObject **);
+PyAPI_FUNC(int) _PyGen_FetchStopIterationValue(PyObject **);
 PyObject *_PyGen_Send(PyGenObject *, PyObject *);
 
 #ifdef __cplusplus
diff --git a/Include/pyerrors.h b/Include/pyerrors.h
index cfae92232f2..2c145ada358 100644
--- a/Include/pyerrors.h
+++ b/Include/pyerrors.h
@@ -400,9 +400,6 @@ PyAPI_FUNC(int) PyUnicodeTranslateError_SetReason(
     const char *reason          /* UTF-8 encoded string */
     );
 
-/* create a StopIteration exception with the given value */
-PyAPI_FUNC(PyObject *) PyStopIteration_Create(PyObject *);
-
 /* These APIs aren't really part of the error implementation, but
    often needed to format error messages; the native C lib APIs are
    not available on all platforms, which is why we provide emulations
diff --git a/Misc/NEWS b/Misc/NEWS
index 6c587af1e25..5a5813b6444 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -111,6 +111,12 @@ Library
 - Issue #14963: Convert contextlib.ExitStack.__exit__ to use an iterative
   algorithm (Patch by Alon Horev)
 
+C-API
+-----
+
+- Issue #13783: Inadvertent additions to the public C API in the PEP 380
+  implementation have either been removed or marked as private interfaces.
+
 Extension Modules
 -----------------
 
diff --git a/Objects/exceptions.c b/Objects/exceptions.c
index 9e10b7e3076..f7066984999 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -516,12 +516,6 @@ StopIteration_traverse(PyStopIterationObject *self, visitproc visit, void *arg)
     return BaseException_traverse((PyBaseExceptionObject *)self, visit, arg);
 }
 
-PyObject *
-PyStopIteration_Create(PyObject *value)
-{
-    return PyObject_CallFunctionObjArgs(PyExc_StopIteration, value, NULL);
-}
-
 ComplexExtendsException(
     PyExc_Exception,       /* base */
     StopIteration,         /* name */
diff --git a/Objects/genobject.c b/Objects/genobject.c
index 8c70b5ca100..6018e5b1a0c 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -97,7 +97,8 @@ gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
             /* Delay exception instantiation if we can */
             PyErr_SetNone(PyExc_StopIteration);
         } else {
-            PyObject *e = PyStopIteration_Create(result);
+            PyObject *e = PyObject_CallFunctionObjArgs(
+                               PyExc_StopIteration, result, NULL);
             if (e != NULL) {
                 PyErr_SetObject(PyExc_StopIteration, e);
                 Py_DECREF(e);
@@ -339,7 +340,7 @@ gen_throw(PyGenObject *gen, PyObject *args)
             Py_DECREF(ret);
             /* Termination repetition of YIELD_FROM */
             gen->gi_frame->f_lasti++;
-            if (PyGen_FetchStopIterationValue(&val) == 0) {
+            if (_PyGen_FetchStopIterationValue(&val) == 0) {
                 ret = gen_send_ex(gen, val, 0);
                 Py_DECREF(val);
             } else {
@@ -428,7 +429,7 @@ gen_iternext(PyGenObject *gen)
  */
 
 int
-PyGen_FetchStopIterationValue(PyObject **pvalue) {
+_PyGen_FetchStopIterationValue(PyObject **pvalue) {
     PyObject *et, *ev, *tb;
     PyObject *value = NULL;
 
diff --git a/Python/ceval.c b/Python/ceval.c
index b3ec013e171..7e9318bc0b3 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1852,7 +1852,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
                 PyObject *val;
                 x = POP(); /* Remove iter from stack */
                 Py_DECREF(x);
-                err = PyGen_FetchStopIterationValue(&val);
+                err = _PyGen_FetchStopIterationValue(&val);
                 if (err < 0) {
                     x = NULL;
                     break;