diff --git a/Modules/md5module.c b/Modules/md5module.c
index b2e65a0..2ae94a4 100644
--- a/Modules/md5module.c
+++ b/Modules/md5module.c
@@ -484,7 +484,7 @@ static PyType_Slot md5_type_slots[] = {
 static PyType_Spec md5_type_spec = {
     .name = "_md5.md5",
     .basicsize =  sizeof(MD5object),
-    .flags = Py_TPFLAGS_DEFAULT,
+    .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,
     .slots = md5_type_slots
 };