diff --git a/src/html/_js_base.html.template b/src/html/_js_base.html.template
index 0824d82b4b..0eea886de2 100644
--- a/src/html/_js_base.html.template
+++ b/src/html/_js_base.html.template
@@ -21,5 +21,5 @@
             "content" in document.createElement("template"))) {
         document.write("<script src='/static/polyfills/webcomponents-bundle.js'><"+"/script>");
       }
-      var isS11_12 = /.*Version\/(?:11|12)(?:\.\d+)*.*Safari\//.test(navigator.userAgent);
+      var isS11_12 = /(?:.*(?:iPhone|iPad).*OS (?:11|12)_\d)|(?:.*Version\/(?:11|12)(?:\.\d+)*.*Safari\/)/.test(navigator.userAgent);
     </script>