diff --git a/tests/test_operations.py b/tests/test_operations.py
index d34f3dd..71b94e5 100644
--- a/tests/test_operations.py
+++ b/tests/test_operations.py
@@ -1,4 +1,5 @@
 import datetime
+import pytest
 from freezegun import freeze_time
 from dateutil.relativedelta import relativedelta
 from datetime import timedelta, tzinfo
@@ -102,3 +103,27 @@ def test_auto_tick() -> None:
     auto_incremented_time = datetime.datetime.now()
     assert first_time + datetime.timedelta(seconds=15) == auto_incremented_time
 
+
+@pytest.mark.parametrize(
+    "tick,expected_diff",
+    (
+        (datetime.timedelta(milliseconds=1500), 1.5),
+        (1, 1),
+        (1.5, 1.5)
+    )
+)
+def test_auto_and_manual_tick(tick, expected_diff) -> None:
+    first_time = datetime.datetime(2020, 1, 14, 0, 0, 0, 1)
+
+    with freeze_time(first_time, auto_tick_seconds=2) as frozen_time:
+        frozen_time.tick(tick)
+        incremented_time = datetime.datetime.now()
+        expected_time = first_time + datetime.timedelta(seconds=expected_diff)
+        assert incremented_time == expected_time
+
+        expected_time += datetime.timedelta(seconds=2)  # auto_tick_seconds
+
+        frozen_time.tick(tick)
+        incremented_time = datetime.datetime.now()
+        expected_time += datetime.timedelta(seconds=expected_diff)
+        assert incremented_time == expected_time