diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index f301b138585a78..7edd94c56214f8 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -4613,11 +4613,10 @@ Array_ass_subscript(PyObject *_self, PyObject *item, PyObject *value)
     else if (PySlice_Check(item)) {
         Py_ssize_t start, stop, step, slicelen, otherlen, i, cur;
 
-        if (PySlice_GetIndicesEx((PySliceObject *)item,
-                                 self->b_length, &start, &stop,
-                                 &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return -1;
         }
+        slicelen = _PySlice_AdjustIndices(self->b_length, &start, &stop, step);
         if ((step < 0 && start < stop) ||
             (step > 0 && start > stop))
             stop = start;
diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index d7f75c902a9d3e..71ffc580712c47 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -1334,11 +1334,11 @@ element_subscr(PyObject* self_, PyObject* item)
         if (!self->extra)
             return PyList_New(0);
 
-        if (PySlice_GetIndicesEx((PySliceObject *)item,
-                self->extra->length,
-                &start, &stop, &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelen = _PySlice_AdjustIndices(self->extra->length, &start, &stop,
+                                         step);
 
         if (slicelen <= 0)
             return PyList_New(0);
@@ -1393,11 +1393,11 @@ element_ass_subscr(PyObject* self_, PyObject* item, PyObject* value)
         if (!self->extra)
             element_new_extra(self, NULL);
 
-        if (PySlice_GetIndicesEx((PySliceObject *)item,
-                self->extra->length,
-                &start, &stop, &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return -1;
         }
+        slicelen = _PySlice_AdjustIndices(self->extra->length, &start, &stop,
+                                         step);
         assert(slicelen <= self->extra->length);
 
         if (value == NULL)
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 9819141c4930e5..310ce7a37e969e 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -1701,10 +1701,11 @@ array_subscr(arrayobject* self, PyObject* item)
         arrayobject* ar;
         int itemsize = self->ob_descr->itemsize;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)item, Py_SIZE(self),
-                         &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(Py_SIZE(self), &start, &stop,
+                                            step);
 
         if (slicelength <= 0) {
             return newarrayobject(&Arraytype, 0, self->ob_descr);
@@ -1772,11 +1773,11 @@ array_ass_subscr(arrayobject* self, PyObject* item, PyObject* value)
             return (*self->ob_descr->setitem)(self, i, value);
     }
     else if (PySlice_Check(item)) {
-        if (PySlice_GetIndicesEx((PySliceObject *)item,
-                                 Py_SIZE(self), &start, &stop,
-                                 &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return -1;
         }
+        slicelength = _PySlice_AdjustIndices(Py_SIZE(self), &start, &stop,
+                                            step);
     }
     else {
         PyErr_SetString(PyExc_TypeError,
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 0dc480599f68ef..4f4c95999c5cd0 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -784,10 +784,10 @@ mmap_subscript(mmap_object *self, PyObject *item)
     else if (PySlice_Check(item)) {
         Py_ssize_t start, stop, step, slicelen;
 
-        if (PySlice_GetIndicesEx((PySliceObject *)item, self->size,
-                         &start, &stop, &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelen = _PySlice_AdjustIndices(self->size, &start, &stop, step);
 
         if (slicelen <= 0)
             return PyString_FromStringAndSize("", 0);
@@ -939,11 +939,10 @@ mmap_ass_subscript(mmap_object *self, PyObject *item, PyObject *value)
     else if (PySlice_Check(item)) {
         Py_ssize_t start, stop, step, slicelen;
 
-        if (PySlice_GetIndicesEx((PySliceObject *)item,
-                                 self->size, &start, &stop,
-                                 &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return -1;
         }
+        slicelen = _PySlice_AdjustIndices(self->size, &start, &stop, step);
         if (value == NULL) {
             PyErr_SetString(PyExc_TypeError,
                 "mmap object doesn't support slice deletion");
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index c74ff0600c8ec7..8c172452661118 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -435,11 +435,11 @@ bytearray_subscript(PyByteArrayObject *self, PyObject *index)
     }
     else if (PySlice_Check(index)) {
         Py_ssize_t start, stop, step, slicelength, cur, i;
-        if (PySlice_GetIndicesEx((PySliceObject *)index,
-                                 PyByteArray_GET_SIZE(self),
-                                 &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)index, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(PyByteArray_GET_SIZE(self),
+                                            &start, &stop, step);
 
         if (slicelength <= 0)
             return PyByteArray_FromStringAndSize("", 0);
@@ -619,11 +619,11 @@ bytearray_ass_subscript(PyByteArrayObject *self, PyObject *index, PyObject *valu
         }
     }
     else if (PySlice_Check(index)) {
-        if (PySlice_GetIndicesEx((PySliceObject *)index,
-                                 PyByteArray_GET_SIZE(self),
-                                 &start, &stop, &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)index, &start, &stop, &step) < 0) {
             return -1;
         }
+        slicelen = _PySlice_AdjustIndices(PyByteArray_GET_SIZE(self), &start,
+                                         &stop, step);
     }
     else {
         PyErr_SetString(PyExc_TypeError, "bytearray indices must be integer");
diff --git a/Objects/listobject.c b/Objects/listobject.c
index a71df7bd2a5bf3..24bb5bbd14a789 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2562,10 +2562,11 @@ list_subscript(PyListObject* self, PyObject* item)
         PyObject* it;
         PyObject **src, **dest;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)item, Py_SIZE(self),
-                         &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(Py_SIZE(self), &start, &stop,
+                                            step);
 
         if (slicelength <= 0) {
             return PyList_New(0);
@@ -2611,10 +2612,11 @@ list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value)
     else if (PySlice_Check(item)) {
         Py_ssize_t start, stop, step, slicelength;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)item, Py_SIZE(self),
-                         &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return -1;
         }
+        slicelength = _PySlice_AdjustIndices(Py_SIZE(self), &start, &stop,
+                                            step);
 
         if (step == 1)
             return list_ass_slice(self, start, stop, value);
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index 2bac266ea7fda5..12be12b00af53f 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -584,10 +584,11 @@ memory_subscript(PyMemoryViewObject *self, PyObject *key)
     else if (PySlice_Check(key)) {
         Py_ssize_t start, stop, step, slicelength;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)key, get_shape0(view),
-                                 &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)key, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(get_shape0(view), &start, &stop,
+                                            step);
     
         if (step == 1 && view->ndim == 1) {
             Py_buffer newview;
@@ -662,10 +663,10 @@ memory_ass_sub(PyMemoryViewObject *self, PyObject *key, PyObject *value)
     else if (PySlice_Check(key)) {
         Py_ssize_t stop, step;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)key, get_shape0(view),
-                         &start, &stop, &step, &len) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)key, &start, &stop, &step) < 0) {
             return -1;
         }
+        len = _PySlice_AdjustIndices(get_shape0(view), &start, &stop, step);
         if (step != 1) {
             PyErr_SetNone(PyExc_NotImplementedError);
             return -1;
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index ff9479e55b0e81..3ac3811853d2cf 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -294,10 +294,10 @@ slice_indices(PySliceObject* self, PyObject* len)
         return NULL;
     }
 
-    if (PySlice_GetIndicesEx(self, ilen, &start, &stop,
-                             &step, &slicelength) < 0) {
+    if (_PySlice_Unpack(self, &start, &stop, &step) < 0) {
         return NULL;
     }
+    slicelength = _PySlice_AdjustIndices(ilen, &start, &stop, step);
 
     return Py_BuildValue("(nnn)", start, stop, step);
 }
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 9b93898c1cce8f..ef4f8c1e19e4df 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1310,11 +1310,11 @@ string_subscript(PyStringObject* self, PyObject* item)
         char* result_buf;
         PyObject* result;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)item,
-                         PyString_GET_SIZE(self),
-                         &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(PyString_GET_SIZE(self), &start,
+                                            &stop, step);
 
         if (slicelength <= 0) {
             return PyString_FromStringAndSize("", 0);
diff --git a/Objects/structseq.c b/Objects/structseq.c
index 75c1ffb0fa476b..9b3ba48a886854 100644
--- a/Objects/structseq.c
+++ b/Objects/structseq.c
@@ -114,11 +114,11 @@ structseq_subscript(PyStructSequence *self, PyObject *item)
         Py_ssize_t start, stop, step, slicelen, cur, i;
         PyObject *result;
 
-        if (PySlice_GetIndicesEx((PySliceObject *)item,
-                                 VISIBLE_SIZE(self), &start, &stop,
-                                 &step, &slicelen) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelen = _PySlice_AdjustIndices(VISIBLE_SIZE(self), &start, &stop,
+                                         step);
         if (slicelen <= 0)
             return PyTuple_New(0);
         result = PyTuple_New(slicelen);
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 2495e95e37946b..808156f7148f23 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -715,11 +715,11 @@ tuplesubscript(PyTupleObject* self, PyObject* item)
         PyObject* it;
         PyObject **src, **dest;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)item,
-                         PyTuple_GET_SIZE(self),
-                         &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(PyTuple_GET_SIZE(self), &start,
+                                            &stop, step);
 
         if (slicelength <= 0) {
             return PyTuple_New(0);
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 7986d70f678ecd..689529ad8b2b0c 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -8008,10 +8008,11 @@ unicode_subscript(PyUnicodeObject* self, PyObject* item)
         Py_UNICODE* result_buf;
         PyObject* result;
 
-        if (PySlice_GetIndicesEx((PySliceObject*)item, PyUnicode_GET_SIZE(self),
-                                 &start, &stop, &step, &slicelength) < 0) {
+        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
             return NULL;
         }
+        slicelength = _PySlice_AdjustIndices(PyUnicode_GET_SIZE(self), &start,
+                                            &stop, step);
 
         if (slicelength <= 0) {
             return PyUnicode_FromUnicode(NULL, 0);