diff --git a/src/_h5ai/private/php/class-bootstrap.php b/src/_h5ai/private/php/class-bootstrap.php
index 3afd7ba4..d67cf586 100644
--- a/src/_h5ai/private/php/class-bootstrap.php
+++ b/src/_h5ai/private/php/class-bootstrap.php
@@ -20,6 +20,7 @@ class Bootstrap {
         } else if ($context->is_info_request()) {
             $public_href = $setup->get('PUBLIC_HREF');
             $x_head_tags = $context->get_x_head_html();
+            $fallback_mode = false;
             require __DIR__ . '/pages/info.php';
         } else {
             $public_href = $setup->get('PUBLIC_HREF');
diff --git a/src/_h5ai/private/php/core/class-setup.php b/src/_h5ai/private/php/core/class-setup.php
index 3e24a558..688767bd 100644
--- a/src/_h5ai/private/php/core/class-setup.php
+++ b/src/_h5ai/private/php/core/class-setup.php
@@ -48,6 +48,7 @@ class Setup {
     private function add_globals_and_envs() {
         $this->set('PHP_VERSION', PHP_VERSION);
         $this->set('MIN_PHP_VERSION', MIN_PHP_VERSION);
+        $this->set('PHP_ARCH', (PHP_INT_SIZE * 8) . '-bit');
 
         $this->set('REQUEST_METHOD', $_SERVER['REQUEST_METHOD']);
         $this->set('REQUEST_HREF', parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH));
@@ -152,6 +153,7 @@ class Setup {
 
                 'PHP_VERSION',
                 'MIN_PHP_VERSION',
+                'PHP_ARCH',
                 'HAS_PHP_EXIF',
                 'HAS_PHP_JPEG',
 
diff --git a/src/_h5ai/public/js/lib/main/info.js b/src/_h5ai/public/js/lib/main/info.js
index 9005bb8a..b90f08fe 100644
--- a/src/_h5ai/public/js/lib/main/info.js
+++ b/src/_h5ai/public/js/lib/main/info.js
@@ -82,6 +82,11 @@ function addTests() {
         true, setup.PHP_VERSION
     );
 
+    addTest(
+        'PHP arch', 'PHP arch is 64-bit',
+        setup.PHP_ARCH === '64-bit', setup.PHP_ARCH
+    );
+
     addTest(
         'Public Cache directory', 'Web server has write access',
         setup.HAS_WRITABLE_CACHE_PUB