diff --git a/tests/unit/transformers/test_datetime.py b/tests/unit/transformers/test_datetime.py
index b8a142b12..685504ff2 100644
--- a/tests/unit/transformers/test_datetime.py
+++ b/tests/unit/transformers/test_datetime.py
@@ -434,7 +434,7 @@ def test__reverse_transform_datetime_format_with_nans(self):
         """Test the ``_reverse_transform`` method returns the correct datetime format with nans."""
         # Setup
         ute = UnixTimestampEncoder()
-        ute.datetime_format = '%b %-d, %Y'
+        ute.datetime_format = '%b %d, %Y'
         transformed = np.array([1.5778368e+18, 1.5805152e+18, np.nan])
         ute._dtype = 'object'
         ute.null_transformer = NullTransformer('mean')
@@ -443,7 +443,7 @@ def test__reverse_transform_datetime_format_with_nans(self):
         output = ute._reverse_transform(transformed)
 
         # Assert
-        expected = pd.Series(['Jan 1, 2020', 'Feb 1, 2020', np.nan])
+        expected = pd.Series(['Jan 01, 2020', 'Feb 01, 2020', np.nan])
         pd.testing.assert_series_equal(output, expected)
 
     def test__reverse_transform_only_nans(self):