diff --git a/test/runner.rb b/test/runner.rb
index 49844c7..8e59a85 100644
--- a/test/runner.rb
+++ b/test/runner.rb
@@ -2,6 +2,8 @@ require 'rbconfig'
 
 require 'test/unit'
 
+require_relative 'ruby/envutil'
+
 src_testdir = File.dirname(File.realpath(__FILE__))
 $LOAD_PATH << src_testdir
 module Gem