--- tcl8.4.12/compat/strstr.c	2005-04-12 20:28:56.000000000 +0200
+++ tcl/compat/strstr.c	2005-12-19 13:35:52.087181048 +0100
@@ -37,7 +37,9 @@
  *
  *----------------------------------------------------------------------
  */
-
+#ifndef NULL
+#define NULL
+#endif
 char *
 strstr(string, substring)
     register char *string;	/* String to search. */