Miro, can you give the following patch a try? diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c index 7916160..ca76a20 100644 --- a/Modules/signalmodule.c +++ b/Modules/signalmodule.c @@ -819,7 +819,6 @@ iterable_to_sigset(PyObject *iterable, sigset_t *mask) int result = -1; PyObject *iterator, *item; long signum; - int err; sigemptyset(mask); @@ -841,11 +840,10 @@ iterable_to_sigset(PyObject *iterable, sigset_t *mask) Py_DECREF(item); if (signum == -1 && PyErr_Occurred()) goto error; - if (0 < signum && signum < NSIG) - err = sigaddset(mask, (int)signum); - else - err = 1; - if (err) { + if (0 < signum && signum < NSIG) { + (void) sigaddset(mask, (int)signum); + } + else { PyErr_Format(PyExc_ValueError, "signal number %ld out of range", signum); goto error;