--- ./src/helpidx.c.org	Sat Nov  5 13:44:26 1994
+++ ./src/helpidx.c	Tue Mar 25 16:16:32 1997
@@ -41,6 +41,10 @@
 #elif ULTRIX
 extern char *optarg;
 extern int optind, opterr;
+#else
+#if defined(__FreeBSD__) && __FreeBSD__ >= 3
+# include <unistd.h>
+#endif
 #endif
 #include <string.h>
 
