diff --git a/tests/test_io.py b/tests/test_io.py
index a95552b8..e733debb 100644
--- a/tests/test_io.py
+++ b/tests/test_io.py
@@ -30,7 +30,7 @@ def setUp(self):
 
         # prep temporary directory
         tempdir = TemporaryDirectory()
-        self.dirname = tempdir.name
+        self.tempdirname = tempdir.name
         self.addCleanup(tempdir.cleanup)
 
     def test_read_mrc_minor_broken(self):