diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index ef4f8c1..c78e193 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1310,7 +1310,7 @@
         char* result_buf;
         PyObject* result;
 
-        if (_PySlice_Unpack((PySliceObject *)item, &start, &stop, &step) < 0) {
+        if (_PySlice_Unpack(item, &start, &stop, &step) < 0) {
             return NULL;
         }
         slicelength = _PySlice_AdjustIndices(PyString_GET_SIZE(self), &start,