diff --git a/test/helper.rb b/test/helper.rb
index 8cd2611..f052b75 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -1,4 +1,4 @@
-require "test-unit"
+require "test/unit"
 require "test/unit/rr"
 require "fluent/test"
 require "fluent/test/driver/input"