Bug: https://bugs.gentoo.org/894522
Upstream PR: https://github.com/linux-on-mac/mbpfan/pull/261
--- a/src/util.c
+++ b/src/util.c
@@ -1,6 +1,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #define __USE_MISC
+#define _BSD_SOURCE
 #include <syslog.h>
 
 #include "global.h"