new file mode 100644
--- /dev/null
+++ b/m4/ullong_max.m4
@@ -0,0 +1,46 @@
+# ullong_max.m4 - define ULLONG_MAX if necessary
+
+dnl Copyright (C) 2005 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.
+
+# Written by Paul Eggert.
+
+AC_DEFUN([gl_ULLONG_MAX],
+[
+  dnl Avoid _AC_COMPUTE_INT-related macros, as they may not work with
+  dnl types wider than long int, due to problems with expr.
+  AC_CACHE_CHECK([for ULLONG_MAX], gl_cv_ullong_max,
+    [gl_cv_ullong_max=no
+     AC_EGREP_CPP([ULLONG_MAX is defined],
+       [
+	#include <limits.h>
+	#ifdef ULLONG_MAX
+	 "ULLONG_MAX is defined"
+	#endif
+       ],
+       [gl_cv_ullong_max=yes])
+     case $gl_cv_ullong_max in
+     no)
+       for gl_expr in \
+	 18446744073709551615ULL \
+	 4722366482869645213695ULL \
+	 340282366920938463463374607431768211455ULL
+       do
+	 AC_TRY_COMPILE([],
+	   [char test[$gl_expr == (unsigned long long int) -1 ? 1 : -1];
+	    static unsigned long long int i = $gl_expr;
+	    return i && test;],
+	   [gl_cv_ullong_max=$gl_expr])
+         test $gl_cv_ullong_max != no && break
+       done
+     esac])
+  case $gl_cv_ullong_max in
+  yes | no) ;;
+  *)
+    AC_DEFINE_UNQUOTED([ULLONG_MAX], [$gl_cv_ullong_max],
+      [Define as the maximum value of the type 'unsigned long long int',
+       if the system doesn't define it, and if the system has that type.]);;
+  esac
+])

new file mode 100644
--- /dev/null
+++ b/modules/ullong_max
@@ -0,0 +1,21 @@
+Description:
+The maximum unsigned long long value, as a preprocessor constant.
+
+Files:
+m4/ullong_max.m4
+
+Depends-on:
+
+configure.ac:
+gl_ULLONG_MAX
+
+Makefile.am:
+
+Include:
+<limits.h>
+
+License:
+GPL
+
+Maintainer:
+Paul Eggert