diff --git a/m4/mbswidth.m4 b/m4/mbswidth.m4
new file mode 100644
index 000000000..d18b26dc5
--- /dev/null
+++ b/m4/mbswidth.m4
@@ -0,0 +1,13 @@
+#serial 1
+
+dnl autoconf tests required for use of mbswidth.c
+dnl From Bruno Haible.
+
+AC_DEFUN(jm_PREREQ_MBSWIDTH,
+[
+  AC_REQUIRE([AC_HEADER_STDC])
+  AC_REQUIRE([AM_C_PROTOTYPES])
+  AC_CHECK_HEADERS(limits.h stdlib.h string.h wchar.h wctype.h)
+  AC_CHECK_FUNCS(isascii iswprint mbrtowc wcwidth)
+  AC_MBSTATE_T
+])