diff --git a/Library/Homebrew/cask/cmd/zap.rb b/Library/Homebrew/cask/cmd/zap.rb
index 7b7eecee8e..d936c0c9f4 100644
--- a/Library/Homebrew/cask/cmd/zap.rb
+++ b/Library/Homebrew/cask/cmd/zap.rb
@@ -23,6 +23,8 @@ module Cask
       end
 
       def run
+        require "cask/installer"
+
         casks.each do |cask|
           odebug "Zapping Cask #{cask}"