diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index e4d7a910..80bd5832 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1433,6 +1433,9 @@ TeX:
   - .dtx
   - .ins
   - .ltx
+  - .mkii
+  - .mkiv
+  = .mkvi
   - .sty
   - .toc