diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index fb8506f5..70d79b7a 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1568,6 +1568,8 @@ Standard ML:
   aliases:
   - sml
   primary_extension: .sml
+  extensions:
+  - .fun
 
 Stylus:
   type: markup