diff --git a/tests/test_compare_vcfs.py b/tests/test_compare_vcfs.py
index 4a6772e..723aab2 100644
--- a/tests/test_compare_vcfs.py
+++ b/tests/test_compare_vcfs.py
@@ -30,14 +30,12 @@ def make_test_case():
             [b'A', b'C'],
             [b'G', b'T'],
         ],
-        dtype='|S1'
     )
     sample_id = np.array(
         [
             'tsk0',
             'tsk1',
         ],
-        dtype='<U4'
     )
     call_genotype = np.array(
         [