diff --git a/app/assets/javascripts/pretty-text/engines/discourse-markdown/html.js.es6 b/app/assets/javascripts/pretty-text/engines/discourse-markdown/html.js.es6
index c3ff79aae4b..64a237ca464 100644
--- a/app/assets/javascripts/pretty-text/engines/discourse-markdown/html.js.es6
+++ b/app/assets/javascripts/pretty-text/engines/discourse-markdown/html.js.es6
@@ -1,5 +1,5 @@
-const BLOCK_TAGS = ['address', 'article', 'aside', 'audio', 'blockquote', 'canvas', 'dd', 'div',
-                    'dl', 'fieldset', 'figcaption', 'figure', 'footer', 'form', 'h1', 'h2', 'h3',
+const BLOCK_TAGS = ['address', 'article', 'aside', 'audio', 'blockquote', 'canvas', 'dd', 'details',
+                    'div', 'dl', 'fieldset', 'figcaption', 'figure', 'footer', 'form', 'h1', 'h2', 'h3',
                     'h4', 'h5', 'h6', 'header', 'hgroup', 'hr', 'iframe', 'noscript', 'ol', 'output',
                     'p', 'pre', 'section', 'table', 'tfoot', 'ul', 'video'];
 
diff --git a/plugins/discourse-details/assets/javascripts/lib/discourse-markdown/details.js.es6 b/plugins/discourse-details/assets/javascripts/lib/discourse-markdown/details.js.es6
index 8416c8ec91d..af0cfca5db1 100644
--- a/plugins/discourse-details/assets/javascripts/lib/discourse-markdown/details.js.es6
+++ b/plugins/discourse-details/assets/javascripts/lib/discourse-markdown/details.js.es6
@@ -12,7 +12,8 @@ function replaceDetails(text) {
 
   // add new lines to make sure we *always* have a <p> element after </summary> and around </details>
   // otherwise we can't hide the content since we can't target text nodes via CSS
-  return text.replace(/<\/summary>/ig, "</summary>\n\n").replace(/<\/details>/ig, "\n\n</details>\n\n");
+  return text.replace(/<\/summary>/ig, "</summary>\n\n")
+             .replace(/<\/details>/ig, "\n\n</details>\n\n");
 }
 
 registerOption((siteSettings, opts) => {
@@ -20,6 +21,12 @@ registerOption((siteSettings, opts) => {
 });
 
 export function setup(helper) {
-  helper.whiteList('details.elided');
+  helper.whiteList([
+    'summary',
+    'summary[title]',
+    'details',
+    'details.elided'
+  ]);
+
   helper.addPreProcessor(text => replaceDetails(text));
 }