diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index 075418e..8748fed 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -169,8 +169,9 @@
 	else {
 		if (!_PyEval_SliceIndex(r->stop, stop)) return -1;
 		if (*stop < 0) *stop += length;
-		if (*stop < 0) *stop = -1;
-		if (*stop > length) *stop = length;
+		if (*stop < 0) *stop = (*step < 0) ? -1 : 0;
+		if (*stop >= length)
+			*stop = (*step < 0) ? length - 1 : length;
 	}
 
 	if ((*step < 0 && *stop >= *start)