diff --git a/unix/m4/iconv.m4 b/unix/m4/iconv.m4
new file mode 100644
index 0000000..654c415
--- /dev/null
+++ b/unix/m4/iconv.m4
@@ -0,0 +1,101 @@
+# iconv.m4 serial AM4 (gettext-0.11.3)
+dnl Copyright (C) 2000-2002 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Bruno Haible.
+
+AC_DEFUN([AM_ICONV_LINKFLAGS_BODY],
+[
+  dnl Prerequisites of AC_LIB_LINKFLAGS_BODY.
+  AC_REQUIRE([AC_LIB_PREPARE_PREFIX])
+  AC_REQUIRE([AC_LIB_RPATH])
+
+  dnl Search for libiconv and define LIBICONV, LTLIBICONV and INCICONV
+  dnl accordingly.
+  AC_LIB_LINKFLAGS_BODY([iconv])
+])
+
+AC_DEFUN([AM_ICONV_LINK],
+[
+  dnl Some systems have iconv in libc, some have it in libiconv (OSF/1 and
+  dnl those with the standalone portable GNU libiconv installed).
+
+  dnl Search for libiconv and define LIBICONV, LTLIBICONV and INCICONV
+  dnl accordingly.
+  AC_REQUIRE([AM_ICONV_LINKFLAGS_BODY])
+
+  dnl Add $INCICONV to CPPFLAGS before performing the following checks,
+  dnl because if the user has installed libiconv and not disabled its use
+  dnl via --without-libiconv-prefix, he wants to use it. The first
+  dnl AC_TRY_LINK will then fail, the second AC_TRY_LINK will succeed.
+  am_save_CPPFLAGS="$CPPFLAGS"
+  AC_LIB_APPENDTOVAR([CPPFLAGS], [$INCICONV])
+
+  AC_CACHE_CHECK(for iconv, am_cv_func_iconv, [
+    am_cv_func_iconv="no, consider installing GNU libiconv"
+    am_cv_lib_iconv=no
+    AC_TRY_LINK([#include <stdlib.h>
+#include <iconv.h>],
+      [iconv_t cd = iconv_open("","");
+       iconv(cd,NULL,NULL,NULL,NULL);
+       iconv_close(cd);],
+      am_cv_func_iconv=yes)
+    if test "$am_cv_func_iconv" != yes; then
+      am_save_LIBS="$LIBS"
+      LIBS="$LIBS $LIBICONV"
+      AC_TRY_LINK([#include <stdlib.h>
+#include <iconv.h>],
+        [iconv_t cd = iconv_open("","");
+         iconv(cd,NULL,NULL,NULL,NULL);
+         iconv_close(cd);],
+        am_cv_lib_iconv=yes
+        am_cv_func_iconv=yes)
+      LIBS="$am_save_LIBS"
+    fi
+  ])
+  if test "$am_cv_func_iconv" = yes; then
+    AC_DEFINE(HAVE_ICONV, 1, [Define if you have the iconv() function.])
+  fi
+  if test "$am_cv_lib_iconv" = yes; then
+    AC_MSG_CHECKING([how to link with libiconv])
+    AC_MSG_RESULT([$LIBICONV])
+  else
+    dnl If $LIBICONV didn't lead to a usable library, we don't need $INCICONV
+    dnl either.
+    CPPFLAGS="$am_save_CPPFLAGS"
+    LIBICONV=
+    LTLIBICONV=
+  fi
+  AC_SUBST(LIBICONV)
+  AC_SUBST(LTLIBICONV)
+])
+
+AC_DEFUN([AM_ICONV],
+[
+  AM_ICONV_LINK
+  if test "$am_cv_func_iconv" = yes; then
+    AC_MSG_CHECKING([for iconv declaration])
+    AC_CACHE_VAL(am_cv_proto_iconv, [
+      AC_TRY_COMPILE([
+#include <stdlib.h>
+#include <iconv.h>
+extern
+#ifdef __cplusplus
+"C"
+#endif
+#if defined(__STDC__) || defined(__cplusplus)
+size_t iconv (iconv_t cd, char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);
+#else
+size_t iconv();
+#endif
+], [], am_cv_proto_iconv_arg1="", am_cv_proto_iconv_arg1="const")
+      am_cv_proto_iconv="extern size_t iconv (iconv_t cd, $am_cv_proto_iconv_arg1 char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);"])
+    am_cv_proto_iconv=`echo "[$]am_cv_proto_iconv" | tr -s ' ' | sed -e 's/( /(/'`
+    AC_MSG_RESULT([$]{ac_t:-
+         }[$]am_cv_proto_iconv)
+    AC_DEFINE_UNQUOTED(ICONV_CONST, $am_cv_proto_iconv_arg1,
+      [Define as const if the declaration of iconv() needs const.])
+  fi
+])