--- configure.ac.orig	2008-03-28 12:49:32.000000000 +0100
+++ configure.ac	2008-05-05 09:47:30.860369561 +0200
@@ -669,20 +669,20 @@
    termcap_curses_order="$ncursesw_test tinfo termcap $ncurses_test curses" ;;
 esac])dnl
 
-AH_TEMPLATE([ZSH_CURSES_NEEDS_XOPEN],
-[Define if the curses libraries need _XOPEN_SOURCE_EXTENDED defined])
-AC_CACHE_CHECK(if the curses library needs _XOPEN_SOURCE_EXTENDED,
-zsh_cv_curses_needs_xopen,
+AH_TEMPLATE([ZSH_NO_XOPEN],
+[Define if _XOPEN_SOURCE_EXTENDED should not be defined to avoid clashes])
+AC_CACHE_CHECK(if _XOPEN_SOURCE_EXTENDED should not be defined,
+zsh_cv_no_xopen,
 [case "$host_os" in
-  *openbsd*)
-  zsh_cv_curses_needs_xopen=no
+  *openbsd*|*freebsd*)
+  zsh_cv_no_xopen=yes
   ;;
   *)
-  zsh_cv_curses_needs_xopen=yes
+  zsh_cv_no_xopen=no
   ;;
 esac])
-if test x$zsh_cv_curses_needs_xopen = xyes; then
-  AC_DEFINE(ZSH_CURSES_NEEDS_XOPEN)
+if test x$zsh_cv_no_xopen = xyes; then
+  AC_DEFINE(ZSH_NO_XOPEN)
 fi
 
 dnl Check for tigetflag (terminfo) before tgetent (termcap).
--- Src/system.h.orig	2007-12-14 13:43:33.000000000 +0100
+++ Src/system.h	2008-05-05 09:50:17.333164563 +0200
@@ -52,9 +52,20 @@
 # undef HAVE_SYS_UTSNAME_H
 #endif
 
-#if defined(ZSH_CURSES_SOURCE) && defined(ZSH_CURSES_NEEDS_XOPEN)
-#define _XOPEN_SOURCE_EXTENDED 1
-#endif
+#ifndef ZSH_NO_XOPEN
+# ifdef ZSH_CURSES_SOURCE
+#  define _XOPEN_SOURCE_EXTENDED 1
+# else
+#  ifdef MULTIBYTE_SUPPORT
+/*
+ * Needed for wcwidth() which is part of XSI.
+ * Various other uses of the interface mean we can't get away with just
+ * _XOPEN_SOURCE.
+ */
+#   define _XOPEN_SOURCE_EXTENDED 1
+#  endif /* MULTIBYTE_SUPPORT */
+# endif /* ZSH_CURSES_SOURCE */
+#endif /* ZSH_NO_XOPEN */
 
 /*
  * Solaris by default zeroes all elements of the tm structure in