diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 7350bb2a..6b94d3cf 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1250,6 +1250,7 @@ Markdown:
   - .md
   - .markdown
   - .mkd
+  - .mkdn
   - .mkdown
   - .ron