--- tcl8.4.9/compat/strstr.c	2002-01-26 03:10:08.000000000 +0200
+++ tcl8.4.9/compat/strstr.c	2005-05-30 06:53:40.000000000 +0300
@@ -33,6 +33,8 @@
  *----------------------------------------------------------------------
  */
 
+#include <unistd.h>
+
 char *
 strstr(string, substring)
     register char *string;	/* String to search. */