--- p64/mkhuff.cc.orig	Sun Nov 28 19:24:42 1999
+++ p64/mkhuff.cc	Sun Nov 28 19:25:49 1999
@@ -45,6 +45,8 @@
 extern "C" {
 int getopt(int, char * const *, const char *);
 }
+#else
+#include <unistd.h>
 #endif
 #define HUFFSTRINGS
 #include "p64-huff.h"