diff --git a/m4/ax_gcc_archflag.m4 b/m4/ax_gcc_archflag.m4
index 6a5e5e3..d4a37f8 100644
--- a/m4/ax_gcc_archflag.m4
+++ b/m4/ax_gcc_archflag.m4
@@ -1,5 +1,5 @@
 # ===========================================================================
-#      http://www.gnu.org/software/autoconf-archive/ax_gcc_archflag.html
+#     https://www.gnu.org/software/autoconf-archive/ax_gcc_archflag.html
 # ===========================================================================
 #
 # SYNOPSIS
@@ -50,7 +50,7 @@
 #   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/>.
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
 #
 #   As a special exception, the respective Autoconf Macro's copyright owner
 #   gives unlimited permission to copy, distribute and modify the configure
@@ -65,7 +65,7 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 18
+#serial 20
 
 AC_DEFUN([AX_GCC_ARCHFLAG],
 [AC_REQUIRE([AC_PROG_CC])
@@ -207,6 +207,13 @@ case $host_cpu in
      cpuarch=`grep 'CPU architecture' /proc/cpuinfo 2> /dev/null | cut -d: -f2 | tr -d " " | head -n 1`
      cpuvar=`grep 'CPU variant' /proc/cpuinfo 2> /dev/null | cut -d: -f2 | tr -d " " | head -n 1`
      case $cpuimpl in
+       0x42) case $cpuarch in
+               8) case $cpuvar in
+                    0x0) ax_gcc_arch="thunderx2t99 vulcan armv8.1-a armv8-a+lse armv8-a native" ;;
+                  esac
+                  ;;
+             esac
+             ;;
        0x43) case $cpuarch in
                8) case $cpuvar in
                     0x0) ax_gcc_arch="thunderx armv8-a native" ;;