diff --git a/spec/dump_methods_spec.rb b/spec/dump_methods_spec.rb
index c49b5dc..5cd31ee 100644
--- a/spec/dump_methods_spec.rb
+++ b/spec/dump_methods_spec.rb
@@ -30,7 +30,7 @@ def expected_output(include_id = false, id_offset = 0)
 
     context 'with file option' do
       before do
-        @filename = Tempfile.new(File.join(Dir.tmpdir, 'foo'), nil)
+        @filename = Tempfile.new('foo', nil)
       end
 
       after do