diff --git a/test/uplot/command_test.rb b/test/uplot/command_test.rb
index 17c6403..f8860fa 100644
--- a/test/uplot/command_test.rb
+++ b/test/uplot/command_test.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative '../test_helper.rb'
+require_relative '../test_helper'
 
 class UplotCommandTest < Test::Unit::TestCase
 end
diff --git a/test/uplot/plot_test.rb b/test/uplot/plot_test.rb
index 625bbe0..985b1eb 100644
--- a/test/uplot/plot_test.rb
+++ b/test/uplot/plot_test.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative '../test_helper.rb'
+require_relative '../test_helper'
 
 class UplotPlotTest < Test::Unit::TestCase
 end
diff --git a/test/uplot/preprocessing_test.rb b/test/uplot/preprocessing_test.rb
index 7f1cc3f..943d901 100644
--- a/test/uplot/preprocessing_test.rb
+++ b/test/uplot/preprocessing_test.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative '../test_helper.rb'
+require_relative '../test_helper'
 
 class UplotPreprocessingTest < Test::Unit::TestCase
   def setup