diff --git a/test/command/test_cat.rb b/test/command/test_cat.rb
index 40605815bb..d74766ac4f 100644
--- a/test/command/test_cat.rb
+++ b/test/command/test_cat.rb
@@ -87,7 +87,7 @@ def test_cat_secondary_file
       d = create_driver
       d.run(expect_records: 1) do
         Open3.pipeline_w("#{ServerEngine.ruby_bin_path} #{FLUENT_CAT_COMMAND} --port #{@port} --format msgpack secondary") do |stdin|
-          stdin.write(File.read(path))
+          stdin.write(File.read(path, File.size(path)))
           stdin.close
         end
       end