diff --git a/homeassistant/components/calendar/__init__.py b/homeassistant/components/calendar/__init__.py
index 86f61f0ed87..b22ac98b0dc 100644
--- a/homeassistant/components/calendar/__init__.py
+++ b/homeassistant/components/calendar/__init__.py
@@ -422,7 +422,7 @@ def _list_events_dict_factory(
     """Convert CalendarEvent dataclass items to dictionary of attributes."""
     return {
         name: value
-        for name, value in obj
+        for name, value in _event_dict_factory(obj).items()
         if name in LIST_EVENT_FIELDS and value is not None
     }
 
diff --git a/tests/components/calendar/conftest.py b/tests/components/calendar/conftest.py
index 4d6b5adfde7..5d506d67c6f 100644
--- a/tests/components/calendar/conftest.py
+++ b/tests/components/calendar/conftest.py
@@ -9,3 +9,11 @@ from homeassistant.setup import async_setup_component
 async def setup_homeassistant(hass: HomeAssistant):
     """Set up the homeassistant integration."""
     await async_setup_component(hass, "homeassistant", {})
+
+
+@pytest.fixture
+def set_time_zone(hass: HomeAssistant) -> None:
+    """Set the time zone for the tests."""
+    # Set our timezone to CST/Regina so we can check calculations
+    # This keeps UTC-6 all year round
+    hass.config.set_time_zone("America/Regina")
diff --git a/tests/components/calendar/test_init.py b/tests/components/calendar/test_init.py
index 9fdc76abe03..463e075d169 100644
--- a/tests/components/calendar/test_init.py
+++ b/tests/components/calendar/test_init.py
@@ -4,8 +4,9 @@ from __future__ import annotations
 from datetime import timedelta
 from http import HTTPStatus
 from typing import Any
-from unittest.mock import ANY, patch
+from unittest.mock import patch
 
+from freezegun import freeze_time
 import pytest
 import voluptuous as vol
 
@@ -386,8 +387,14 @@ async def test_create_event_service_invalid_params(
         )
 
 
-async def test_list_events_service(hass: HomeAssistant) -> None:
-    """Test listing events from the service call using exlplicit start and end time."""
+@freeze_time("2023-06-22 10:30:00+00:00")
+async def test_list_events_service(hass: HomeAssistant, set_time_zone: None) -> None:
+    """Test listing events from the service call using exlplicit start and end time.
+
+    This test uses a fixed date/time so that it can deterministically test the
+    string output values.
+    """
+
     await async_setup_component(hass, "calendar", {"calendar": {"platform": "demo"}})
     await hass.async_block_till_done()
 
@@ -408,8 +415,8 @@ async def test_list_events_service(hass: HomeAssistant) -> None:
     assert response == {
         "events": [
             {
-                "start": ANY,
-                "end": ANY,
+                "start": "2023-06-22T05:00:00-06:00",
+                "end": "2023-06-22T06:00:00-06:00",
                 "summary": "Future Event",
                 "description": "Future Description",
                 "location": "Future Location",
diff --git a/tests/components/calendar/test_trigger.py b/tests/components/calendar/test_trigger.py
index 05c7d95d8ad..45dd9d6afe1 100644
--- a/tests/components/calendar/test_trigger.py
+++ b/tests/components/calendar/test_trigger.py
@@ -121,14 +121,6 @@ class FakeSchedule:
             await self.fire_time(dt_util.utcnow())
 
 
-@pytest.fixture
-def set_time_zone(hass: HomeAssistant) -> None:
-    """Set the time zone for the tests."""
-    # Set our timezone to CST/Regina so we can check calculations
-    # This keeps UTC-6 all year round
-    hass.config.set_time_zone("America/Regina")
-
-
 @pytest.fixture
 def fake_schedule(
     hass: HomeAssistant, freezer: FrozenDateTimeFactory