diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 5f118ce..9eda4bd 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -226,7 +226,8 @@
         return NULL;
     }
     self = PyTuple_GET_ITEM(args, 0);
-    if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
+    if (!_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
+                                  (PyObject *)(descr->d_type))) {
         PyErr_Format(PyExc_TypeError,
                      "descriptor '%V' "
                      "requires a '%.100s' object "
@@ -284,7 +285,8 @@
         return NULL;
     }
     self = PyTuple_GET_ITEM(args, 0);
-    if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
+    if (!_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
+                                  (PyObject *)(descr->d_type))) {
         PyErr_Format(PyExc_TypeError,
                      "descriptor '%V' "
                      "requires a '%.100s' object "
@@ -1065,7 +1067,8 @@
 
     assert(PyObject_TypeCheck(d, &PyWrapperDescr_Type));
     descr = (PyWrapperDescrObject *)d;
-    assert(PyObject_IsInstance(self, (PyObject *)(descr->d_type)));
+    assert(_PyObject_RealIsSubclass((PyObject *)Py_TYPE(self),
+                                    (PyObject *)(descr->d_type)));
 
     wp = PyObject_GC_New(wrapperobject, &wrappertype);
     if (wp != NULL) {