diff --git a/libs/idris-html/src/Iwf/Html.idr b/libs/idris-html/src/Iwf/Html.idr
index 052af23..10b50d1 100644
--- a/libs/idris-html/src/Iwf/Html.idr
+++ b/libs/idris-html/src/Iwf/Html.idr
@@ -1149,6 +1149,7 @@ knownHtmlAttributes =
   , "itemscope", "itemtype", "lang", "popover", "spellcheck", "translate"
   , "href", "target", "rel", "download", "hreflang", "media", "ping", "referrerpolicy"
   , "src", "srcset", "sizes", "alt", "width", "height", "loading", "decoding"
+  , "sandbox", "allow", "allowfullscreen", "srcdoc"
   , "type", "name", "value", "placeholder", "disabled", "checked", "readonly", "required"
   , "multiple", "selected", "autocomplete", "autoplay", "controls", "loop", "muted", "playsinline"
   , "action", "method", "enctype", "novalidate", "for", "form", "min", "max", "step", "pattern"