diff --git a/tests/unit/test_io_hdf5_h5tools.py b/tests/unit/test_io_hdf5_h5tools.py
index d19a186a9..6a1213713 100644
--- a/tests/unit/test_io_hdf5_h5tools.py
+++ b/tests/unit/test_io_hdf5_h5tools.py
@@ -3709,6 +3709,7 @@ def test_set_data_io_old_api(self):
         with self.assertWarnsWith(DeprecationWarning, msg):
             self.obj.set_data_io("data1", H5DataIO, chunks=True)
         self.assertIsInstance(self.obj.data1, H5DataIO)
+        self.assertTrue(self.obj.data1.chunks)
 
 
 class TestDataSetDataIO(TestCase):