diff --git a/Python/ceval.c b/Python/ceval.c
index 6e5e272..e56e957 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4360,7 +4360,7 @@
             Py_INCREF(self);
             func = PyMethod_GET_FUNCTION(func);
             Py_INCREF(func);
-            Py_SETREF(*pfunc, self);
+            Py_XSETREF(*pfunc, self);
             na++;
             n++;
         } else