--- a/source4/auth/gensec/pygensec.c    2019-12-08 00:22:20.834666099 +0100
+++ b/source4/auth/gensec/pygensec.c    2019-12-08 16:51:01.432729335 +0100
@@ -678,7 +678,7 @@
 		"S.have_feature()\n Return True if GENSEC negotiated a particular feature." },
 	{ "set_max_update_size",  (PyCFunction)py_gensec_set_max_update_size, METH_VARARGS,
 		"S.set_max_update_size(max_size) \n Some mechs can fragment update packets, needs to be use before the mech is started." },
-	{ "max_update_size",  (PyCFunction)py_gensec_max_update_size, 0,
+	{ "max_update_size",  (PyCFunction)py_gensec_max_update_size, METH_NOARGS,
 		"S.max_update_size() \n Return the current max_update_size." },
 	{ "update",  (PyCFunction)py_gensec_update, METH_VARARGS,
 		"S.update(blob_in) -> (finished, blob_out)\nPerform one step in a GENSEC dance.  Repeat with new packets until finished is true or exception." },