diff --git a/tests/unit/materializations/incremental/test_microbatch.py b/tests/unit/materializations/incremental/test_microbatch.py
index 06519d4994c..ed5415c0f0b 100644
--- a/tests/unit/materializations/incremental/test_microbatch.py
+++ b/tests/unit/materializations/incremental/test_microbatch.py
@@ -605,6 +605,7 @@ def test_truncate_timestamp(self, timestamp, batch_size, expected_timestamp):
     @pytest.mark.parametrize(
         "batch_size,start_time,expected_formatted_start_time",
         [
+            (BatchSize.year, None, ""),
             (BatchSize.year, datetime(2020, 1, 1, 1), "20200101"),
             (BatchSize.month, datetime(2020, 1, 1, 1), "20200101"),
             (BatchSize.day, datetime(2020, 1, 1, 1), "20200101"),
@@ -617,6 +618,7 @@ def test_batch_id(self, batch_size, start_time, expected_formatted_start_time):
     @pytest.mark.parametrize(
         "batch_size,batch_start,expected_formatted_batch_start",
         [
+            (BatchSize.year, None, ""),
             (BatchSize.year, datetime(2020, 1, 1, 1), "20200101"),
             (BatchSize.month, datetime(2020, 1, 1, 1), "20200101"),
             (BatchSize.day, datetime(2020, 1, 1, 1), "20200101"),