diff --git a/app/assets/javascripts/discourse/dialects/dialect.js b/app/assets/javascripts/discourse/dialects/dialect.js
index ddb84b45a8d..749b289fced 100644
--- a/app/assets/javascripts/discourse/dialects/dialect.js
+++ b/app/assets/javascripts/discourse/dialects/dialect.js
@@ -11,7 +11,8 @@ var parser = window.BetterMarkdown,
     dialect = MD.dialects.Discourse = DialectHelpers.subclassDialect( MD.dialects.Gruber ),
     initialized = false,
     emitters = [],
-    hoisted;
+    hoisted,
+    preProcessors = [];
 
 /**
   Initialize our dialects for processing.
@@ -165,6 +166,11 @@ Discourse.Dialect = {
   **/
   cook: function(text, opts) {
     if (!initialized) { initializeDialects(); }
+
+    preProcessors.forEach(function(p) {
+      text = p(text);
+    });
+
     hoisted = {};
     dialect.options = opts;
     var tree = parser.toHTMLTree(text, 'Discourse'),
@@ -188,6 +194,14 @@ Discourse.Dialect = {
     return result.trim();
   },
 
+  /**
+    Adds a text pre-processor. Use only if necessary, as a dialect
+    that emits JsonML is much better if possible.
+  **/
+  addPreProcessor: function(preProc) {
+    preProcessors.push(preProc);
+  },
+
   /**
     Registers an inline replacer function
 
diff --git a/app/assets/javascripts/discourse/lib/markdown.js b/app/assets/javascripts/discourse/lib/markdown.js
index 89f9b471fe2..b9861f78147 100644
--- a/app/assets/javascripts/discourse/lib/markdown.js
+++ b/app/assets/javascripts/discourse/lib/markdown.js
@@ -9,7 +9,8 @@
 **/
 var _validClasses = {},
     _validIframes = [],
-    _validTags = {};
+    _validTags = {},
+    _decoratedCaja = false;
 
 function validateAttribute(tagName, attribName, value) {
   var tag = _validTags[tagName];
@@ -198,6 +199,20 @@ Discourse.Markdown = {
     // Allow things like <3 and <_<
     text = text.replace(/<([^A-Za-z\/\!]|$)/g, "&lt;$1");
 
+    // The first time, let's add some more whitelisted tags
+    if (!_decoratedCaja) {
+
+      // Add anything whitelisted to the list of elements if it's not in there
+      // already.
+      var elements = window.html4.ELEMENTS;
+      Ember.keys(_validTags).forEach(function(t) {
+        if (!elements[t]) {
+          elements[t] = 0;
+        }
+      });
+      _decoratedCaja = true;
+    }
+
     return window.html_sanitize(text, Discourse.Markdown.urlAllowed, validateAttribute);
   },