diff --git a/test/drb/ut_array.rb b/test/drb/ut_array.rb
index 6d9778f..8ff001d 100644
--- a/test/drb/ut_array.rb
+++ b/test/drb/ut_array.rb
@@ -8,7 +8,7 @@ if __FILE__ == $0
     it
   end
 
-  DRb.start_service(nil, [1, 2, 'III', 4, "five", 6])
+  DRb.start_service('druby://localhost:0', [1, 2, 'III', 4, "five", 6])
   es = DRb::ExtServ.new(ARGV.shift, ARGV.shift)
   DRb.thread.join
 end
diff --git a/test/drb/ut_array_drbssl.rb b/test/drb/ut_array_drbssl.rb
index 5644af5..4c4edca 100644
--- a/test/drb/ut_array_drbssl.rb
+++ b/test/drb/ut_array_drbssl.rb
@@ -17,7 +17,7 @@ if __FILE__ == $0
   config[:SSLCertName] =
     [ ["C","JP"], ["O","Foo.DRuby.Org"], ["CN", "Sample"] ]
 
-  DRb.start_service('drbssl://:0', [1, 2, 'III', 4, "five", 6], config)
+  DRb.start_service('drbssl://localhost:0', [1, 2, 'III', 4, "five", 6], config)
   es = DRb::ExtServ.new(ARGV.shift, ARGV.shift)
   DRb.thread.join
 end
diff --git a/test/drb/ut_eq.rb b/test/drb/ut_eq.rb
index 330af95..0f68ac1 100644
--- a/test/drb/ut_eq.rb
+++ b/test/drb/ut_eq.rb
@@ -24,7 +24,7 @@ if __FILE__ == $0
     it
   end
 
-  DRb.start_service('druby://:0', Bar.new)
+  DRb.start_service('druby://localhost:0', Bar.new)
   es = DRb::ExtServ.new(ARGV.shift, ARGV.shift)
   DRb.thread.join
 end