diff --git a/test/ruby/test_process.rb b/test/ruby/test_process.rb
index 32c12fcdc6..dfe91f2888 100644
--- a/test/ruby/test_process.rb
+++ b/test/ruby/test_process.rb
@@ -1,6 +1,5 @@
 require 'test/unit'
 require 'tempfile'
-require 'pathname'
 require 'timeout'
 require_relative 'envutil'
 require 'rbconfig'
@@ -28,7 +27,7 @@ class TestProcess < Test::Unit::TestCase
 
   def with_tmpchdir
     Dir.mktmpdir {|d|
-      d = Pathname.new(d).realpath.to_s
+      d = File.realpath(d)
       Dir.chdir(d) {
         yield d
       }