diff --git a/tests/utils/test_datetime.py b/tests/utils/test_datetime.py
index e9529b6d3e..429a2f9629 100644
--- a/tests/utils/test_datetime.py
+++ b/tests/utils/test_datetime.py
@@ -14,6 +14,7 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
+import re
 from datetime import datetime, time, timezone, tzinfo
 
 import pytest
@@ -123,6 +124,11 @@ def test_timestamp_to_nanos_unexpected_zone_offset() -> None:
         timestamp_to_nanos("2025-02-23T16:21:44.375612001-04:00")
 
 
+def test_timestamp_to_nanos_invalid_timestamp() -> None:
+    with pytest.raises(ValueError, match=re.escape("Invalid timestamp without zone: invalid (must be ISO-8601)")):
+        timestamp_to_nanos("invalid")
+
+
 @pytest.mark.parametrize(
     "timestamp, nanos",
     [
@@ -140,6 +146,11 @@ def test_timestamptz_to_nanos_missing_zone_offset() -> None:
         timestamptz_to_nanos("2025-02-23T20:21:44.375612001")
 
 
+def test_timestamptz_to_nanos_invalid_timestamp() -> None:
+    with pytest.raises(ValueError, match=re.escape("Invalid timestamp with zone: invalid (must be ISO-8601)")):
+        timestamptz_to_nanos("invalid")
+
+
 @pytest.mark.parametrize("nanos, micros", [(1510871468000001001, 1510871468000001), (-1510871468000001001, -1510871468000002)])
 def test_nanos_to_micros(nanos: int, micros: int) -> None:
     assert micros == nanos_to_micros(nanos)