diff --git a/Library/Homebrew/cask/cmd/upgrade.rb b/Library/Homebrew/cask/cmd/upgrade.rb
index 36a926e6aa..8bab75d853 100644
--- a/Library/Homebrew/cask/cmd/upgrade.rb
+++ b/Library/Homebrew/cask/cmd/upgrade.rb
@@ -28,11 +28,11 @@ module Cask
 
         ohai "Casks with `auto_updates` or `version :latest` will not be upgraded" if args.empty? && !greedy?
         oh1 "Upgrading #{Formatter.pluralize(outdated_casks.length, "outdated package")}, with result:"
-        cask_upgrades = outdated_casks.map do |f|
-          if f.installed_caskfile.nil?
-            "#{f.full_name} #{f.version}"
+        cask_upgrades = outdated_casks.map do |cask|
+          if cask.installed_caskfile.nil?
+            "#{cask.full_name} #{cask.version}"
           else
-            "#{f.full_name} #{CaskLoader.load(f.installed_caskfile).version} -> #{f.version}"
+            "#{cask.full_name} #{CaskLoader.load(cask.installed_caskfile).version} -> #{cask.version}"
           end
         end
         puts cask_upgrades.join(", ")