diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index b3cc8103..c85fe463 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -748,6 +748,7 @@ Forth:
   - .fth
   - .4th
   - .forth
+  - .frt
 
 Frege:
   type: programming