diff --git a/django_mongodb/base.py b/django_mongodb/base.py
index 92c85cb1..79e21660 100644
--- a/django_mongodb/base.py
+++ b/django_mongodb/base.py
@@ -145,7 +145,6 @@ def _connect(self):
         self.connection = MongoClient(
             host=settings_dict["HOST"] or None,
             port=int(settings_dict["PORT"] or 27017),
-            tz_aware=True,
             **options,
         )
         db_name = settings_dict["NAME"]
diff --git a/django_mongodb/features.py b/django_mongodb/features.py
index 08c7cbe2..bf04ecf0 100644
--- a/django_mongodb/features.py
+++ b/django_mongodb/features.py
@@ -7,6 +7,8 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     supports_ignore_conflicts = False
     # Not implemented: https://github.com/mongodb-labs/django-mongodb/issues/8
     supports_json_field = False
+    # MongoDB stores datetimes in UTC.
+    supports_timezones = False
     # Not implemented: https://github.com/mongodb-labs/django-mongodb/issues/7
     supports_transactions = False
     uses_savepoints = False
@@ -20,7 +22,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "basic.tests.ModelLookupTest.test_does_not_exist",
         "basic.tests.ModelLookupTest.test_equal_lookup",
         "basic.tests.ModelLookupTest.test_rich_lookup",
-        "basic.tests.ModelTest.test_year_lookup_edge_case",
         "lookup.tests.LookupTests.test_chain_date_time_lookups",
         "lookup.test_timefield.TimeFieldLookupTests.test_hour_lookups",
         "lookup.test_timefield.TimeFieldLookupTests.test_minute_lookups",
@@ -286,8 +287,8 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             "timezones.tests.LegacyDatabaseTests.test_cursor_execute_accepts_naive_datetime",
             "timezones.tests.LegacyDatabaseTests.test_cursor_execute_returns_naive_datetime",
             "timezones.tests.LegacyDatabaseTests.test_raw_sql",
-            "timezones.tests.NewDatabaseTests.test_cursor_execute_accepts_aware_datetime",
-            "timezones.tests.NewDatabaseTests.test_cursor_execute_returns_aware_datetime",
+            "timezones.tests.NewDatabaseTests.test_cursor_execute_accepts_naive_datetime",
+            "timezones.tests.NewDatabaseTests.test_cursor_execute_returns_naive_datetime",
             "timezones.tests.NewDatabaseTests.test_cursor_explicit_time_zone",
             "timezones.tests.NewDatabaseTests.test_raw_sql",
         },
diff --git a/django_mongodb/operations.py b/django_mongodb/operations.py
index 4b210321..311c799c 100644
--- a/django_mongodb/operations.py
+++ b/django_mongodb/operations.py
@@ -17,8 +17,16 @@ def adapt_datefield_value(self, value):
         return datetime.datetime.combine(value, datetime.datetime.min.time())
 
     def adapt_datetimefield_value(self, value):
-        if not settings.USE_TZ and value is not None and timezone.is_naive(value):
-            value = timezone.make_aware(value)
+        if value is None:
+            return None
+        if timezone.is_aware(value):
+            if settings.USE_TZ:
+                value = timezone.make_naive(value, self.connection.timezone)
+            else:
+                raise ValueError(
+                    "MongoDB backend does not support timezone-aware "
+                    "datetimes when USE_TZ is False."
+                )
         return value
 
     def adapt_decimalfield_value(self, value, max_digits=None, decimal_places=None):
@@ -31,6 +39,8 @@ def adapt_timefield_value(self, value):
         """Store TimeField as datetime."""
         if value is None:
             return None
+        if timezone.is_aware(value):
+            raise ValueError("MongoDB backend does not support timezone-aware times.")
         return datetime.datetime.combine(datetime.datetime.min.date(), value)
 
     def get_db_converters(self, expression):
@@ -39,7 +49,7 @@ def get_db_converters(self, expression):
         if internal_type == "DateField":
             converters.append(self.convert_datefield_value)
         elif internal_type == "DateTimeField":
-            if not settings.USE_TZ:
+            if settings.USE_TZ:
                 converters.append(self.convert_datetimefield_value)
         elif internal_type == "DecimalField":
             converters.append(self.convert_decimalfield_value)
@@ -56,8 +66,7 @@ def convert_datefield_value(self, value, expression, connection):
 
     def convert_datetimefield_value(self, value, expression, connection):
         if value is not None:
-            # Django expects naive datetimes when settings.USE_TZ is False.
-            value = timezone.make_naive(value)
+            value = timezone.make_aware(value, self.connection.timezone)
         return value
 
     def convert_decimalfield_value(self, value, expression, connection):