diff --git a/tools/python/genwrap.py b/tools/python/genwrap.py
index fd2d39dd6e..314e39dacf 100644
--- a/tools/python/genwrap.py
+++ b/tools/python/genwrap.py
@@ -151,7 +151,7 @@ static PyTypeObject Py%s_Type= {
     NULL,                         /* tp_getattro       */
     NULL,                         /* tp_setattro       */
     NULL,                         /* tp_as_buffer      */
-    Py_TPFLAGS_DEFAULT,           /* tp_flags          */
+    Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /* tp_flags          */
     "%s",                         /* tp_doc            */
     NULL,                         /* tp_traverse       */
     NULL,                         /* tp_clear          */
diff --git a/tools/python/xen/lowlevel/xl/xl.c b/tools/python/xen/lowlevel/xl/xl.c
index 9b47153f73..9b5dcd3cd7 100644
--- a/tools/python/xen/lowlevel/xl/xl.c
+++ b/tools/python/xen/lowlevel/xl/xl.c
@@ -628,7 +628,7 @@ static PyTypeObject PyXlType = {
     NULL,                         /* tp_getattro       */
     NULL,                         /* tp_setattro       */
     NULL,                         /* tp_as_buffer      */
-    Py_TPFLAGS_DEFAULT,           /* tp_flags          */
+    Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE, /* tp_flags          */
     "libxenlight connection",     /* tp_doc            */
     NULL,                         /* tp_traverse       */
     NULL,                         /* tp_clear          */