diff --git a/webstead.xhtml b/webstead.xhtml
index 61a261e..c3bb0c1 100644
--- a/webstead.xhtml
+++ b/webstead.xhtml
@@ -38,7 +38,10 @@
           background: currentColor;
       }
     </style>
-    <script type="module"><![CDATA[
+    <!-- Script is async rather than deferred because Chromium can't
+         handle deferred scripts in XHTML.
+         https://issues.chromium.org/issues/40518469 -->
+    <script type="module" async="async"><![CDATA[
     import Bedstead from './bedstead.js';
     function update_glyph() {
         var args = [];
@@ -71,10 +74,19 @@
             }
         });
     }
-    for (var e of document.getElementsByTagName('input')) {
-        e.onchange = update_glyph;
+    function init() {
+        for (var e of document.getElementsByTagName('input')) {
+            e.onchange = update_glyph;
+        }
+        update_glyph();
+    }
+    // This script is loaded asynchronously, so make sure the DOM is
+    // loaded before touching it.
+    if (document.readyState === "loading") {
+        document.addEventListener("DOMContentLoaded", init);
+    } else {
+        init();
     }
-    update_glyph();
 ]]>
     </script>
   </head>