--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-03-31  Simon Josefsson  <simon@josefsson.org>
+
+	* modules/u64-tests: New file.
+	* tests/test-u64.c: New file.
+
 2009-03-04  Simon Josefsson  <simon@josefsson.org>
 
 	* MODULES.html.sh: Mention u64.

new file mode 100644
--- /dev/null
+++ b/modules/u64-tests
@@ -0,0 +1,6 @@
+Files:
+tests/test-u64.c
+
+Makefile.am:
+TESTS += test-u64
+check_PROGRAMS += test-u64

new file mode 100644
--- /dev/null
+++ b/tests/test-u64.c
@@ -0,0 +1,47 @@
+/* Test of <u64.h>
+   Copyright (C) 2009 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Simon Josefsson <simon@josefsson.org>, 2009.  */
+
+#include <config.h>
+
+#include <u64.h>
+
+int
+main ()
+{
+  u64 i = u64init (42, 4711);
+  u64 j, k, l;
+
+  j = u64hilo (42, 4711);
+
+  if (u64lt (i, j) || u64lt (j, i))
+    return 1;
+
+  i = u64hilo (0, 42);
+  j = u64hilo (0, 43);
+
+  if (!u64lt (i, j))
+    return 1;
+
+  k = u64plus (i, j);
+  l = u64hilo (0, 42 + 43);
+
+  if (u64lt (k, l) || u64lt (l, k))
+    return 1;
+
+  return 0;
+}