diff --git a/Modules/_bisectmodule.c b/Modules/_bisectmodule.c
index 4469dc0..fc54954 100644
--- a/Modules/_bisectmodule.c
+++ b/Modules/_bisectmodule.c
@@ -82,7 +82,7 @@
 	index = internal_bisect_right(list, item, lo, hi);
 	if (index < 0)
 		return NULL;
-	if (PyList_Check(list)) {
+	if (PyList_CheckExact(list)) {
 		if (PyList_Insert(list, index, item) < 0)
 			return NULL;
 	} else {
@@ -183,7 +183,7 @@
 	index = internal_bisect_left(list, item, lo, hi);
 	if (index < 0)
 		return NULL;
-	if (PyList_Check(list)) {
+	if (PyList_CheckExact(list)) {
 		if (PyList_Insert(list, index, item) < 0)
 			return NULL;
 	} else {