--- knock-0.5.old/src/knockd.c	2005-06-27 07:11:34.000000000 +0200
+++ knock-0.5/src/knockd.c	2008-07-25 22:38:08.000000000 +0200
@@ -19,6 +19,7 @@
  *  USA.
  */
 
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>