diff --git a/ogn_python/backend/liveglidernet.py b/ogn_python/backend/liveglidernet.py
index d23ee9e..726438c 100644
--- a/ogn_python/backend/liveglidernet.py
+++ b/ogn_python/backend/liveglidernet.py
@@ -4,6 +4,8 @@ from sqlalchemy import func, and_, between, case
 
 from ogn_python.model import AircraftBeacon, Device, Receiver
 
+from ogn_python import db
+
 
 def utc_to_local(utc_dt):
     return utc_dt.replace(tzinfo=timezone.utc).astimezone(tz=None)
@@ -17,9 +19,9 @@ def decode(code):
     return code[2:9]
 
 
-def rec(session):
+def rec():
     last_10_minutes = datetime.utcnow() - timedelta(minutes=10)
-    receiver_query = session.query(Receiver,
+    receiver_query = db.session.query(Receiver,
                                    case([(Receiver.lastseen > last_10_minutes, True)],
                                         else_=False).label('is_online')) \
         .order_by(Receiver.name)
@@ -38,14 +40,14 @@ def rec(session):
     return xml
 
 
-def lxml(session, show_offline=False, lat_max=90, lat_min=-90, lon_max=180, lon_min=-180):
+def lxml(show_offline=False, lat_max=90, lat_min=-90, lon_max=180, lon_min=-180):
 
     if show_offline:
         observation_start = date.today()
     else:
         observation_start = datetime.utcnow() - timedelta(minutes=5)
 
-    position_query = session.query(AircraftBeacon, Device) \
+    position_query = db.session.query(AircraftBeacon, Device) \
         .filter(and_(between(func.ST_Y(AircraftBeacon.location_wkt), lat_min, lat_max),
                      between(func.ST_X(AircraftBeacon.location_wkt), lon_min, lon_max))) \
         .filter(Device.lastseen > observation_start) \
diff --git a/ogn_python/backend/ognrange.py b/ogn_python/backend/ognrange.py
index bf2732e..468e470 100644
--- a/ogn_python/backend/ognrange.py
+++ b/ogn_python/backend/ognrange.py
@@ -5,6 +5,8 @@ from sqlalchemy import func, case
 from sqlalchemy.sql.expression import label
 from ogn_python.model import Receiver
 
+from ogn_python import db
+
 
 def alchemyencoder(obj):
     """JSON encoder function for SQLAlchemy special classes."""
@@ -17,10 +19,10 @@ def alchemyencoder(obj):
         return float(obj)
 
 
-def stations2_filtered_pl(session):
+def stations2_filtered_pl():
     last_10_minutes = datetime.utcnow() - timedelta(minutes=10)
 
-    query = session.query(
+    query = db.session.query(
         Receiver.name.label('s'),
         label('lt', func.round(func.ST_Y(Receiver.location_wkt) * 10000) / 10000),
         label('lg', func.round(func.ST_X(Receiver.location_wkt) * 10000) / 10000),
@@ -30,7 +32,7 @@ def stations2_filtered_pl(session):
         label('v', Receiver.version + '.' + Receiver.platform)) \
         .order_by(Receiver.lastseen)
 
-    res = session.execute(query)
+    res = db.session.execute(query)
     stations = json.dumps({'stations': [dict(r) for r in res]}, default=alchemyencoder)
 
     return stations
diff --git a/tests/backend/test_backends.py b/tests/backend/test_backends.py
index 329f36d..26284a1 100644
--- a/tests/backend/test_backends.py
+++ b/tests/backend/test_backends.py
@@ -51,7 +51,7 @@ class TestDB(TestBaseDB, XmlTestMixin):
     def test_rec(self, datetime_mock):
         datetime_mock.utcnow.return_value = datetime(2017, 12, 20, 10, 0)
 
-        data = rec(db.session).encode(encoding='utf-8')
+        data = rec().encode(encoding='utf-8')
 
         # Check the document
         root = self.assertXmlDocument(data)
@@ -75,7 +75,7 @@ class TestDB(TestBaseDB, XmlTestMixin):
     def test_lxml(self, datetime_mock, utc_to_local_mock):
         datetime_mock.utcnow.return_value = datetime(2017, 12, 20, 10, 0, 5)
 
-        data = lxml(db.session).encode(encoding='utf-8')
+        data = lxml().encode(encoding='utf-8')
 
         # Check the complete document
         expected = """<?xml version="1.0" encoding="UTF-8"?>
@@ -91,7 +91,7 @@ class TestDB(TestBaseDB, XmlTestMixin):
     def test_stations2_filtered_pl(self, datetime_mock):
         datetime_mock.utcnow.return_value = datetime(2017, 12, 20, 10, 0)
 
-        result = stations2_filtered_pl(db.session)
+        result = stations2_filtered_pl()
 
         data = json.loads(result)
 
diff --git a/tests/base.py b/tests/base.py
index 784f322..9ee150e 100644
--- a/tests/base.py
+++ b/tests/base.py
@@ -23,6 +23,11 @@ class TestBaseDB(unittest.TestCase):
             DELETE FROM receiver_beacons;
             DELETE FROM takeoff_landings;
             DELETE FROM logbook;
+            DELETE FROM receiver_coverages;
+            DELETE FROM device_stats;
+            DELETE FROM receiver_stats;
+            DELETE FROM receivers;
+            DELETE FROM devices;
         """)