Hans Leidekker (@hans) commented about dlls/wbemprox/builtin.c:
idx = 0; while (SetupDiEnumDeviceInfo( device_info_set, idx++, &devinfo )) {
WCHAR device_id[MAX_PATH];
WCHAR guid[40] = {0};
WCHAR device_id[MAX_PATH], guid[GUID_SIZE] = {0};
There's no need to initialize guid. Otherwise it looks good.