--- sem.c.orig	Wed Jul 14 17:59:18 1993
+++ sem.c	Thu Apr 13 23:20:09 2017
@@ -26,6 +26,7 @@
 /* This is a simple module to provide an easier to understand interface to
  * semaphores */
 
+#include <unistd.h>
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -94,7 +95,7 @@ new_sems( nsems )
 	return sem;
 }
 
-static
+static void
 do_sem( sem_id, pbuf, err )
 	int sem_id;
 	struct sembuf *pbuf;