diff --git a/Library/Homebrew/cask/migrator.rb b/Library/Homebrew/cask/migrator.rb
index 1b96488695..8df853aae8 100644
--- a/Library/Homebrew/cask/migrator.rb
+++ b/Library/Homebrew/cask/migrator.rb
@@ -80,6 +80,7 @@ module Cask
       when ".json"
         json = JSON.parse(path.read)
         json["token"] = new_token
+        json["old_tokens"] = (json["old_tokens"] << old_token).uniq
         path.atomic_write json.to_json
       end
     end