diff --git a/test/test_timeseries_api.py b/test/test_timeseries_api.py
index 1fe0837..37ccc58 100644
--- a/test/test_timeseries_api.py
+++ b/test/test_timeseries_api.py
@@ -22,6 +22,15 @@
 TESTED = timeseries_api.__name__
 
 
+class dt_eq:
+
+    def __init__(self, value: utils.DatetimeSrc_) -> None:
+        self.value = utils.parse_datetime(value)
+
+    def __eq__(self, __value: object) -> bool:
+        return self.value == utils.parse_datetime(__value)
+
+
 @pytest.fixture
 async def m_victoria(mocker):
     m = mocker.patch(TESTED + '.victoria.CV').get.return_value
@@ -103,7 +112,6 @@ async def test_ranges(client: AsyncClient, m_victoria: Mock):
 
 async def test_metrics(client: AsyncClient, m_victoria: Mock):
     now = time_ns() // 1_000_000
-    now_str = utils.format_datetime(now, 'ISO8601')
     m_victoria.metrics.return_value = [
         TimeSeriesMetric(
             metric='a',
@@ -124,9 +132,9 @@ async def test_metrics(client: AsyncClient, m_victoria: Mock):
 
     resp = await client.post('/timeseries/metrics', json={'fields': ['a', 'b', 'c']})
     assert resp.json() == [
-        {'metric': 'a', 'value': approx(1.2), 'timestamp': now_str},
-        {'metric': 'b', 'value': approx(2.2), 'timestamp': now_str},
-        {'metric': 'c', 'value': approx(3.2), 'timestamp': now_str},
+        {'metric': 'a', 'value': approx(1.2), 'timestamp': dt_eq(now)},
+        {'metric': 'b', 'value': approx(2.2), 'timestamp': dt_eq(now)},
+        {'metric': 'c', 'value': approx(3.2), 'timestamp': dt_eq(now)},
     ]
 
     resp = await client.post('/timeseries/metrics', json={})
@@ -273,7 +281,7 @@ async def test_stream_error(sync_client: TestClient, m_victoria: Mock):
         TimeSeriesMetric(
             metric='a',
             value=1.2,
-            timestamp=datetime(2021, 7, 15, 19, tzinfo=timezone.utc)
+            timestamp=dt
         ),
     ]
 
@@ -311,7 +319,7 @@ async def test_stream_error(sync_client: TestClient, m_victoria: Mock):
                 'metrics': [{
                     'metric': 'a',
                     'value': approx(1.2),
-                    'timestamp': utils.format_datetime(dt, 'ISO8601'),
+                    'timestamp': dt_eq(dt),
                 }],
             },
         }
diff --git a/test/test_utils.py b/test/test_utils.py
index 9a3d98b..6b59713 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -40,7 +40,7 @@ def test_parse_datetime():
 
 def test_format_datetime():
     time_s = 1626359370
-    iso_str = '2021-07-15T14:29:30.000000Z'
+    iso_str = '2021-07-15T14:29:30Z'
     time_ms = time_s * 1000
     dt = datetime.fromtimestamp(time_s, tz=timezone.utc)
 
diff --git a/test/test_victoria.py b/test/test_victoria.py
index 61208ec..589c5eb 100644
--- a/test/test_victoria.py
+++ b/test/test_victoria.py
@@ -122,7 +122,7 @@ async def test_metrics(client: AsyncClient,
     assert result == [
         TimeSeriesMetric(metric='service/f1',
                          value=1,
-                         timestamp=now()),
+                         timestamp=now),
         TimeSeriesMetric(metric='service/f2',
                          value=2,
                          timestamp=now),