diff --git a/configure.ac b/configure.ac
index 681ba6d..c55f274 100644
--- a/configure.ac
+++ b/configure.ac
@@ -16,7 +16,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-AC_PREREQ(2.61)
+AC_PREREQ([2.63])
 
 AC_INIT([GNU diffutils],
         m4_esyscmd([build-aux/git-version-gen .tarball-version]),