diff --git a/extras/iconv.m4 b/extras/iconv.m4
new file mode 100644
index 0000000..7320bef
--- /dev/null
+++ b/extras/iconv.m4
@@ -0,0 +1,39 @@
+#serial 1
+
+dnl From Bruno Haible.
+
+AC_DEFUN(jm_ICONV,
+[
+  dnl Some systems have iconv in libc, some have it in libiconv (OSF/1 and
+  dnl those with the standalone portable libiconv installed).
+  AC_CACHE_CHECK(for iconv, jm_cv_func_iconv, [
+    jm_cv_func_iconv="no, consider installing libiconv"
+    jm_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);],
+      jm_cv_func_iconv=yes)
+    if test "$jm_cv_func_iconv" != yes; then
+      jm_save_LIBS="$LIBS"
+      LIBS="$LIBS -liconv"
+      AC_TRY_LINK([#include <stdlib.h>
+#include <iconv.h>],
+        [iconv_t cd = iconv_open("","");
+         iconv(cd,NULL,NULL,NULL,NULL);
+         iconv_close(cd);],
+        jm_cv_lib_iconv=yes
+        jm_cv_func_iconv=yes)
+      LIBS="$jm_save_LIBS"
+    fi
+  ])
+  if test "$jm_cv_func_iconv" = yes; then
+    AC_DEFINE(HAVE_ICONV, 1, [Define if you have the iconv() function.])
+  fi
+  LIBICONV=
+  if test "$jm_cv_lib_iconv" = yes; then
+    LIBICONV="-liconv"
+  fi
+  AC_SUBST(LIBICONV)
+])