diff --git a/test/drb/drbtest.rb b/test/drb/drbtest.rb
index ab6b59a322..c9e768ad9d 100644
--- a/test/drb/drbtest.rb
+++ b/test/drb/drbtest.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: false
 require 'test/unit'
+require 'envutil'
 require 'drb/drb'
 require 'drb/extservm'
 require 'timeout'
diff --git a/test/rinda/test_rinda.rb b/test/rinda/test_rinda.rb
index 615bba6623..69ac64eb44 100644
--- a/test/rinda/test_rinda.rb
+++ b/test/rinda/test_rinda.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: false
 require 'test/unit'
+require 'envutil'
 
 require 'drb/drb'
 require 'drb/eq'