https://bugs.gentoo.org/919000
https://www.riverbankcomputing.com/hg/sip/rev/afc99fa84d0d

diff --git a/siplib.c b/siplib.c
index 8b0a6d5..d996a9c 100644
--- a/siplib.c
+++ b/siplib.c
@@ -3902,7 +3902,7 @@ static int parsePass1(PyObject **parseErrp, sipSimpleWrapper **selfp,
     {
     case '#':
             /* A ctor has an argument with the /Transfer/ annotation. */
-            *selfp = va_arg(va, PyObject *);
+            *selfp = (sipSimpleWrapper *) va_arg(va, PyObject *);
             break;
 
     case 'B':