diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index a0ac57f1..e3032c9b 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -511,6 +511,7 @@ JavaScript:
   - .jsm
   - .jss
   - .jsx
+  - .pac
   - .sjs
   - .ssjs
   filenames: