diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index d82c846..d16dbba 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -550,6 +550,11 @@
         for code in 'xXobns':
             self.assertRaises(ValueError, format, 0, ',' + code)
 
+    def test_internal_sizes(self):
+        self.assertGreater(object.__basicsize__, 0)
+        self.assertGreater(tuple.__itemsize__, 0)
+
+
 def test_main():
     run_unittest(TypesTests)
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 6d3d497..ecb1a4f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
 Core and Builtins
 -----------------
 
+- Issue #9688: __basicsize__ and __itemsize__ must be accessed as Py_ssize_t.
+
 - Issue #9684: Added a definition for SIZEOF_WCHAR_T to PC/pyconfig.h,
   to match the pyconfig.h generated by configure on other systems.
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 1babcb6..8b74e1e 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -189,8 +189,8 @@
 
 
 static PyMemberDef type_members[] = {
-    {"__basicsize__", T_INT, offsetof(PyTypeObject,tp_basicsize),READONLY},
-    {"__itemsize__", T_INT, offsetof(PyTypeObject, tp_itemsize), READONLY},
+    {"__basicsize__", T_PYSSIZET, offsetof(PyTypeObject,tp_basicsize),READONLY},
+    {"__itemsize__", T_PYSSIZET, offsetof(PyTypeObject, tp_itemsize), READONLY},
     {"__flags__", T_LONG, offsetof(PyTypeObject, tp_flags), READONLY},
     {"__weakrefoffset__", T_LONG,
      offsetof(PyTypeObject, tp_weaklistoffset), READONLY},