diff --git a/t/bin/lines.rb b/t/bin/lines.rb
index 2d4765e..0966e5d 100755
--- a/t/bin/lines.rb
+++ b/t/bin/lines.rb
@@ -1,6 +1,14 @@
 #!/usr/bin/ruby
 
-for line in ARGV
-    puts line
-end
+out = STDOUT
 
+for line in ARGV
+    case line
+    when "--stdout"
+        out = STDOUT
+    when "--stderr"
+        out = STDERR
+    else
+        out.puts(line)
+    end
+end