diff --git a/Include/object.h b/Include/object.h
index 4ee1f8e..8fe202d 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -824,6 +824,29 @@
 #define Py_XINCREF(op) do { if ((op) == NULL) ; else Py_INCREF(op); } while (0)
 #define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
 
+/* Safely decref `op` and set `op` to `op2`.
+ *
+ * As in case of Py_CLEAR "the obvious" code can be deadly:
+ *
+ *     Py_XDECREF(op);
+ *     op = op2;
+ *
+ * The safe way is:
+ *
+ *      Py_SETREF(op, op2);
+ *
+ * That arranges to set `op` to `op2` _before_ decref'ing, so that any code
+ * triggered as a side-effect of `op` getting torn down no longer believes
+ * `op` points to a valid object.
+ */
+
+#define Py_SETREF(op, op2)                      \
+    do {                                        \
+        PyObject *_py_tmp = (PyObject *)(op);   \
+        (op) = (op2);                           \
+        Py_XDECREF(_py_tmp);                    \
+    } while (0)
+
 /*
 These are provided as conveniences to Python runtime embedders, so that
 they can have object code that is not dependent on Python compilation flags.