diff --git a/History.txt b/History.txt
index 3895619b..5e415d54 100644
--- a/History.txt
+++ b/History.txt
@@ -1,6 +1,8 @@
 ==
   * Bug Fixes
     * Require redcloth >= 4.2.1 in tests (#92)
+  * Minor Enhancements
+    * Allow .mkd as markdown extension
 
 == 0.5.5
   * Bug Fixes
diff --git a/lib/jekyll/convertible.rb b/lib/jekyll/convertible.rb
index f0348ab5..3e733d72 100644
--- a/lib/jekyll/convertible.rb
+++ b/lib/jekyll/convertible.rb
@@ -49,7 +49,7 @@ module Jekyll
       case self.ext[1..-1]
       when /textile/i
         return 'textile'
-      when /markdown/i, /mkdn/i, /md/i
+      when /markdown/i, /mkdn/i, /md/i, /mkd/i
         return 'markdown'
       end
       return 'unknown'