diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 737f226a..5f492c54 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1265,6 +1265,8 @@ TeX:
   - .dtx
   - .ins
   - .ltx
+  - .mkii
+  - .mkiv
   - .sty
   - .toc