@@ -3488,11 +3488,11 @@ get_bases_tuple(PyObject *bases_in, PyType_Spec *spec)
 }
 
 static inline int
-check_basicsize_includes_size_and_offsets(PyTypeObject* type)
+type_check_basicsize_includes_size_and_offsets(PyTypeObject* type)
 {
     if (type->tp_alloc != PyType_GenericAlloc) {
         // Custom allocators can ignore tp_basicsize
-        return 1;
+        return 0;
     }
     Py_ssize_t max = (Py_ssize_t)type->tp_basicsize;
 
@@ -3501,30 +3501,30 @@ check_basicsize_includes_size_and_offsets(PyTypeObject* type)
                      "tp_basicsize for type '%s' (%d) is too small for base '%s' (%d)",
                      type->tp_name, type->tp_basicsize,
                      type->tp_base->tp_name, type->tp_base->tp_basicsize);
-        return 0;
+        return -1;
     }
     if (type->tp_weaklistoffset + (Py_ssize_t)sizeof(PyObject*) > max) {
         PyErr_Format(PyExc_TypeError,
                      "weaklist offset %d is out of bounds for type '%s' (tp_basicsize = %d)",
                      type->tp_weaklistoffset,
                      type->tp_name, type->tp_basicsize);
-        return 0;
+        return -1;
     }
     if (type->tp_dictoffset + (Py_ssize_t)sizeof(PyObject*) > max) {
         PyErr_Format(PyExc_TypeError,
                      "dict offset %d is out of bounds for type '%s' (tp_basicsize = %d)",
                      type->tp_dictoffset,
                      type->tp_name, type->tp_basicsize);
-        return 0;
+        return -1;
     }
     if (type->tp_vectorcall_offset + (Py_ssize_t)sizeof(vectorcallfunc*) > max) {
         PyErr_Format(PyExc_TypeError,
                      "vectorcall offset %d is out of bounds for type '%s' (tp_basicsize = %d)",
                      type->tp_vectorcall_offset,
                      type->tp_name, type->tp_basicsize);
-        return 0;
+        return -1;
     }
-    return 1;
+    return 0;
 }
 
 PyObject *
@@ -3825,10 +3825,6 @@ PyType_FromMetaclass(PyTypeObject *metaclass, PyObject *module,
         goto finally;
     }
 
-    if (!check_basicsize_includes_size_and_offsets(type)) {
-        goto finally;
-    }
-
     if (type->tp_doc) {
         PyObject *__doc__ = PyUnicode_FromString(_PyType_DocWithoutSignature(type->tp_name, type->tp_doc));
         if (!__doc__) {
@@ -6869,6 +6865,9 @@ type_ready(PyTypeObject *type)
     if (type_ready_managed_dict(type) < 0) {
         return -1;
     }
+    if (type_check_basicsize_includes_size_and_offsets(type) < 0) {
+        return -1;
+    }
     if (type_ready_post_checks(type) < 0) {
         return -1;
     }