diff --git a/app/assets/javascripts/defer/html-sanitizer-bundle.js b/app/assets/javascripts/defer/html-sanitizer-bundle.js
index 0886fb5ece6..12b212e535e 100644
--- a/app/assets/javascripts/defer/html-sanitizer-bundle.js
+++ b/app/assets/javascripts/defer/html-sanitizer-bundle.js
@@ -883,9 +883,6 @@ html4.ATTRIBS = {
   'ol::type': 0,
   'p::align': 0,
   'pre::width': 0,
-  'progress::max': 0,
-  'progress::min': 0,
-  'progress::value': 0,
   'q::cite': 1,
   'source::type': 0,
   'track::default': 0,
@@ -965,7 +962,6 @@ html4.ELEMENTS = {
   'legend': 0,
   'li': 1,
   'link': 274,
-  'mark': 0,
   'meter': 0,
   'nav': 0,
   'nobr': 0,
@@ -977,7 +973,6 @@ html4.ELEMENTS = {
   'p': 1,
   'param': 274,
   'pre': 0,
-  'progress': 0,
   'q': 0,
   's': 0,
   'samp': 0,
@@ -1076,7 +1071,6 @@ html4.ELEMENT_DOM_INTERFACES = {
   'li': 'HTMLLIElement',
   'link': 'HTMLLinkElement',
   'map': 'HTMLMapElement',
-  'mark': 'HTMLElement',
   'menu': 'HTMLMenuElement',
   'meta': 'HTMLMetaElement',
   'meter': 'HTMLMeterElement',
@@ -1093,7 +1087,6 @@ html4.ELEMENT_DOM_INTERFACES = {
   'p': 'HTMLParagraphElement',
   'param': 'HTMLParamElement',
   'pre': 'HTMLPreElement',
-  'progress': 'HTMLProgressElement',
   'q': 'HTMLQuoteElement',
   's': 'HTMLElement',
   'samp': 'HTMLElement',
diff --git a/test/javascripts/lib/markdown_test.js b/test/javascripts/lib/markdown_test.js
index 1b76655707b..863be7f3e02 100644
--- a/test/javascripts/lib/markdown_test.js
+++ b/test/javascripts/lib/markdown_test.js
@@ -365,6 +365,8 @@ test("sanitize", function() {
   equal(sanitize("<textarea>hullo</textarea>"), "hullo");
   equal(sanitize("<button>press me!</button>"), "press me!");
   equal(sanitize("<canvas>draw me!</canvas>"), "draw me!");
+  equal(sanitize("<progress>hello"), "hello");
+  equal(sanitize("<mark>highlight</mark>"), "highlight");
 
   cooked("[the answer](javascript:alert(42))", "<p><a>the answer</a></p>", "it prevents XSS");