diff --git a/src/inet.c b/src/inet.c
index be21481..edec03a 100644
--- a/src/inet.c
+++ b/src/inet.c
@@ -37,6 +37,7 @@ static char *id = "$Id: inet.c,v 1.3 2001/12/24 01:09:03 sybalsky Exp $ Copyrigh
 #include <netdb.h>
 #include <sys/ioctl.h>
 #include <errno.h>
+#include <unistd.h>
 #endif /* DOS */
 #include "lispemul.h"
 #include "lispmap.h"