diff --git a/xcode/build_phases/multiple_swiftlint/strategy_maker.rb b/xcode/build_phases/multiple_swiftlint/strategy_maker.rb
index eb82ae4..d297dbf 100644
--- a/xcode/build_phases/multiple_swiftlint/strategy_maker.rb
+++ b/xcode/build_phases/multiple_swiftlint/strategy_maker.rb
@@ -1,4 +1,5 @@
 require 'fileutils'
+require 'tmpdir'
 
 require_relative 'array_extension.rb'
 require_relative 'git_caretaker.rb'