diff --git a/src/netcalc.h b/src/netcalc.h
index b31d669..0e5c30b 100644
--- a/src/netcalc.h
+++ b/src/netcalc.h
@@ -32,6 +32,9 @@
 #include <config.h>
 #include <stdint.h>
 #include <err.h>		/* warnx() et al */
+#ifdef __APPLE__
+#include <sys/socket.h> /* Has to be included before net/if.h */
+#endif
 #include <net/if.h>		/* IFNAMSIZ */
 
 #define V4ADDR_VAL "0123456789."