1 files changed, 2 insertions, 0 deletions
diff --git a/Objects/classobject.c b/Objects/classobject.c
index 71c4a4e..12dc276 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -48,6 +48,7 @@ method_vectorcall(PyObject *method, PyObject *const *args,
     PyObject *self = PyMethod_GET_SELF(method);
     PyObject *func = PyMethod_GET_FUNCTION(method);
     Py_ssize_t nargs = PyVectorcall_NARGS(nargsf);
+    assert(nargs == 0 || args[nargs-1]);
 
     PyObject *result;
     if (nargsf & PY_VECTORCALL_ARGUMENTS_OFFSET) {
@@ -56,6 +57,7 @@ method_vectorcall(PyObject *method, PyObject *const *args,
         nargs += 1;
         PyObject *tmp = newargs[0];
         newargs[0] = self;
+        assert(newargs[nargs-1]);
         result = _PyObject_VectorcallTstate(tstate, func, newargs,
                                             nargs, kwnames);
         newargs[0] = tmp;