diff --git a/api/ovdashboard_api/core/calevent.py b/api/ovdashboard_api/core/calevent.py
index c22bbca..aa523e1 100644
--- a/api/ovdashboard_api/core/calevent.py
+++ b/api/ovdashboard_api/core/calevent.py
@@ -6,16 +6,26 @@ Caches events using `timed_alru_cache`.
 
 import functools
 import logging
-from datetime import datetime
+from datetime import UTC, datetime
 from typing import Annotated, Self
 
-from pydantic import BaseModel, ConfigDict, StringConstraints
+from pydantic import AfterValidator, BaseModel, ConfigDict, StringConstraints
 from vobject.base import Component
 
 _logger = logging.getLogger(__name__)
 type StrippedStr = Annotated[str, StringConstraints(strip_whitespace=True)]
 
 
+def make_utc(v: datetime) -> datetime:
+    if v.tzinfo is None:
+        return v.replace(tzinfo=UTC)
+
+    return v
+
+
+type UTCDateTime = Annotated[datetime, AfterValidator(make_utc)]
+
+
 @functools.total_ordering
 class CalEvent(BaseModel):
     """
@@ -31,8 +41,8 @@ class CalEvent(BaseModel):
 
     summary: StrippedStr = ""
     description: StrippedStr = ""
-    dtstart: datetime = datetime.now()
-    dtend: datetime = datetime.now()
+    dtstart: UTCDateTime = datetime.now(UTC)
+    dtend: UTCDateTime = datetime.now(UTC)
 
     def __lt__(self, other: Self) -> bool:
         """
@@ -64,6 +74,9 @@ class CalEvent(BaseModel):
             except KeyError:
                 pass
 
+        print(event)
+        print(data)
+
         if "dtend" not in data:
             data["dtend"] = data["dtstart"]
 
diff --git a/api/ovdashboard_api/core/dav/caldav.py b/api/ovdashboard_api/core/dav/caldav.py
index 3a0acb7..8ac5108 100644
--- a/api/ovdashboard_api/core/dav/caldav.py
+++ b/api/ovdashboard_api/core/dav/caldav.py
@@ -1,5 +1,5 @@
 import logging
-from datetime import datetime, timedelta
+from datetime import UTC, datetime, timedelta
 from typing import cast
 
 from asyncify import asyncify
@@ -69,7 +69,7 @@ class CalDAV:
         _logger.info(f"downloading {calendar_name!r} ...")
 
         dt_start = datetime.combine(
-            datetime.now().date(),
+            datetime.now(UTC).date(),
             datetime.min.time(),
         )
         dt_end = dt_start + timedelta(days=cfg.calendar.future_days)