--- arg/arg.orig	2013-11-13 11:44:52.000000000 +0100
+++ arg/arg	2013-11-27 16:37:01.000000000 +0100
@@ -5,6 +5,9 @@
         Singleton Class built around getopt() and getopt_long() (3)
 */
 
+#ifdef __FreeBSD__
+#include <errno.h>
+#endif
 
 #include <string>
 #include <vector>