diff --git a/lib/util/date_extension.dart b/lib/util/date_extension.dart
index bf12ddbea21c87937a018937a100d1c5beec9200..272d082bb374a8ccc35c34ee1525e62b344b65c7 100644
--- a/lib/util/date_extension.dart
+++ b/lib/util/date_extension.dart
@@ -23,8 +23,12 @@ extension DateExtension on DateTime {
     return '$dd.$mm.$year';
   }
 
+  DateTime atStartOfDay() {
+    return DateTime(year, month, day);
+  }
+
   DateTime atStartOfWeek() {
     final date = subtract(Duration(days: weekday - 1));
-    return DateTime(date.year, date.month, date.day);
+    return date.atStartOfDay();
   }
 }
diff --git a/test/start_of_week_test.dart b/test/start_of_datetime_test.dart
similarity index 74%
rename from test/start_of_week_test.dart
rename to test/start_of_datetime_test.dart
index 745f47ba057393c7b6335490a32592dea3ba915a..5fee05919dfc9ecc6bb0d0b45cd3d72827bf49bf 100644
--- a/test/start_of_week_test.dart
+++ b/test/start_of_datetime_test.dart
@@ -30,4 +30,14 @@ void main() {
 
     expect(startOfWeek, startOfNextMonday);
   });
+
+  test('Start of day at 00:00', () {
+    final startOfWeek = DateTime(2023, 3, 21, 0, 0).atStartOfDay();
+    expect(startOfWeek, DateTime(2023, 3, 21, 0, 0));
+  });
+
+  test('Start of day at 23:59', () {
+    final startOfWeek = DateTime(2023, 3, 21, 23, 59).atStartOfDay();
+    expect(startOfWeek, DateTime(2023, 3, 21, 00, 00));
+  });
 }