Gnulib requires autoconf 2.64 now.
Signed-off-by: Simon Josefsson <simon@josefsson.org>
diff --git a/configure.ac b/configure.ac
index 1fd5c97..83aa493 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([2.63])
+AC_PREREQ([2.64])
AC_INIT([GNU Libtasn1],[4.16.0],[help-libtasn1@gnu.org])
AC_CONFIG_AUX_DIR([build-aux])
AC_CONFIG_MACRO_DIRS([m4 m4-gl])
