diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index 271a9ad..d8a2465 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -252,7 +252,7 @@
 {
 	Py_ssize_t ilen, start, stop, step, slicelength;
 
-	ilen = PyInt_AsSsize_t(len);
+	ilen = PyNumber_AsSsize_t(len, PyExc_OverflowError);
 
 	if (ilen == -1 && PyErr_Occurred()) {
 		return NULL;