diff --git a/src/HtmlUtils.js b/src/HtmlUtils.js
index 63ee5fa480..671f9b4955 100644
--- a/src/HtmlUtils.js
+++ b/src/HtmlUtils.js
@@ -143,7 +143,7 @@ export function processHtmlForSending(html: string): string {
  * of that HTML.
  */
 export function sanitizedHtmlNode(insaneHtml) {
-    const saneHtml =  sanitizeHtml(insaneHtml, sanitizeHtmlParams);
+    const saneHtml = sanitizeHtml(insaneHtml, sanitizeHtmlParams);
 
     return <div dangerouslySetInnerHTML={{ __html: saneHtml }} dir="auto" />;
 }
@@ -152,7 +152,7 @@ const sanitizeHtmlParams = {
     allowedTags: [
         'font', // custom to matrix for IRC-style font coloring
         'del', // for markdown
-        'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote', 'p', 'a', 'ul', 'ol',
+        'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote', 'p', 'a', 'ul', 'ol', 'sup', 'sub',
         'nl', 'li', 'b', 'i', 'u', 'strong', 'em', 'strike', 'code', 'hr', 'br', 'div',
         'table', 'thead', 'caption', 'tbody', 'tr', 'th', 'td', 'pre', 'span', 'img',
     ],
diff --git a/src/Markdown.js b/src/Markdown.js
index 6e735c6f0e..455d5e95bd 100644
--- a/src/Markdown.js
+++ b/src/Markdown.js
@@ -17,7 +17,7 @@ limitations under the License.
 import commonmark from 'commonmark';
 import escape from 'lodash/escape';
 
-const ALLOWED_HTML_TAGS = ['del', 'u'];
+const ALLOWED_HTML_TAGS = ['sub', 'sup', 'del', 'u'];
 
 // These types of node are definitely text
 const TEXT_NODES = ['text', 'softbreak', 'linebreak', 'paragraph', 'document'];