diff --git a/Library/Homebrew/cask/cmd/brew-cask-tests.rb b/Library/Homebrew/cask/cmd/brew-cask-tests.rb
index 94902e41c5..002d357ddd 100755
--- a/Library/Homebrew/cask/cmd/brew-cask-tests.rb
+++ b/Library/Homebrew/cask/cmd/brew-cask-tests.rb
@@ -21,6 +21,8 @@ repo_root.cd do
     system "bundle", "install"
   end
 
+  require "bundler/setup"
+
   rspec = ARGV.flag?("--rspec") || !ARGV.flag?("--minitest")
   minitest = ARGV.flag?("--minitest") || !ARGV.flag?("--rspec")