diff --git a/app/assets/javascripts/discourse/dialects/code_dialect.js b/app/assets/javascripts/discourse/dialects/code_dialect.js
index 8ef0545296b..0eb5c738a0d 100644
--- a/app/assets/javascripts/discourse/dialects/code_dialect.js
+++ b/app/assets/javascripts/discourse/dialects/code_dialect.js
@@ -3,12 +3,12 @@
 **/
 
 var acceptableCodeClasses =
-  ["lang-auto", "1c", "actionscript", "apache", "applescript", "avrasm", "axapta", "bash", "brainfuck",
+  ["auto", "1c", "actionscript", "apache", "applescript", "avrasm", "axapta", "bash", "brainfuck",
    "clojure", "cmake", "coffeescript", "cpp", "cs", "css", "d", "delphi", "diff", "xml", "django", "dos",
    "erlang-repl", "erlang", "glsl", "go", "handlebars", "haskell", "http", "ini", "java", "javascript",
-   "json", "lisp", "lua", "markdown", "matlab", "mel", "nginx", "objectivec", "parser3", "perl", "php",
-   "profile", "python", "r", "rib", "rsl", "ruby", "rust", "scala", "smalltalk", "sql", "tex", "text",
-   "vala", "vbscript", "vhdl"];
+   "json", "lisp", "lua", "markdown", "matlab", "mel", "nginx", "nohighlight", "objectivec", "parser3",
+   "perl", "php", "profile", "python", "r", "rib", "rsl", "ruby", "rust", "scala", "smalltalk", "sql",
+   "tex", "text", "vala", "vbscript", "vhdl"];
 
 var textCodeClasses = ["text", "pre"];
 
@@ -32,9 +32,9 @@ Discourse.Dialect.replaceBlock({
     }
 
     if (textCodeClasses.indexOf(matches[1]) !== -1) {
-      return ['p', ['pre', ['code', flattenBlocks(blockContents) ]]];
+      return ['p', ['pre', ['code', {'class': 'lang-nohighlight'}, flattenBlocks(blockContents) ]]];
     } else  {
-      return ['p', ['pre', ['code', {'class': klass}, flattenBlocks(blockContents) ]]];
+      return ['p', ['pre', ['code', {'class': 'lang-' + klass}, flattenBlocks(blockContents) ]]];
     }
   }
 });
@@ -69,3 +69,7 @@ Discourse.Dialect.replaceBlock({
     return ['p', ['pre', flattenBlocks(blockContents)]];
   }
 });
+
+// Whitelist the language classes
+var regexpSource = "^lang-(" + acceptableCodeClasses.join('|') + ")$";
+Discourse.Markdown.whiteListTag('code', 'class', new RegExp(regexpSource, "i"));
diff --git a/app/assets/javascripts/discourse/lib/markdown.js b/app/assets/javascripts/discourse/lib/markdown.js
index f00ad7d696f..040cb3a87f2 100644
--- a/app/assets/javascripts/discourse/lib/markdown.js
+++ b/app/assets/javascripts/discourse/lib/markdown.js
@@ -301,14 +301,6 @@ Discourse.Markdown.whiteListTag('img', 'src', /^data:image.*$/i);
 Discourse.Markdown.whiteListTag('div', 'class', 'title');
 Discourse.Markdown.whiteListTag('div', 'class', 'quote-controls');
 
-// explicitly whitelist classes we need allowed through for
-// syntax highlighting, grabbed from highlight.js
-hljs.listLanguages().forEach(function (language) {
-  Discourse.Markdown.whiteListTag('code', 'class', language);
-});
-Discourse.Markdown.whiteListTag('code', 'class', 'text');
-Discourse.Markdown.whiteListTag('code', 'class', 'lang-auto');
-
 Discourse.Markdown.whiteListTag('span', 'class', 'mention');
 Discourse.Markdown.whiteListTag('span', 'class', 'spoiler');
 Discourse.Markdown.whiteListTag('div', 'class', 'spoiler');
diff --git a/config/site_settings.yml b/config/site_settings.yml
index 24c190cc241..5fc756b3320 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -374,7 +374,7 @@ posting:
     default: 10000
   default_code_lang:
     client: true
-    default: "lang-auto"
+    default: "auto"
   warn_reviving_old_topic_age: 180
   autohighlight_all_code:
     client: true