diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index d7f0fe91b3..a9d5fa4953 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -80,7 +80,8 @@ File.validOptions = [
   // these are used by plugins
   "ignore",
   "only",
-  "extensions"
+  "extensions",
+  "accept"
 ];
 
 File.normaliseOptions = function (opts) {