diff --git a/lib/github/markup/markdown.rb b/lib/github/markup/markdown.rb
index 5b17afb7..1b927a80 100644
--- a/lib/github/markup/markdown.rb
+++ b/lib/github/markup/markdown.rb
@@ -112,8 +112,8 @@ class Markdown < Implementation
 
       def initialize
         super(
-          /md|mkdn?|mdwn|mdown|markdown|mdx|litcoffee/i,
-          ["Markdown", "MDX", "Literate CoffeeScript"])
+          /md|mkdn?|mdwn|mdown|markdown|litcoffee/i,
+          ["Markdown", "Literate CoffeeScript"])
       end
 
       def load