diff --git a/sourcing/model.py b/sourcing/model.py
index 6a2a145..e2cf5fc 100644
--- a/sourcing/model.py
+++ b/sourcing/model.py
@@ -140,13 +140,15 @@ class Item(TimeStampedModel):
     text = Column(UnicodeText)
 
     subjects = relationship('Item',
+                            lazy='dynamic',
                             secondary='reference',
-                            backref='object_item',
-                           foreign_keys=Reference.subject_id)
+                            primaryjoin=id == Reference.object_id,
+                            secondaryjoin=id == Reference.subject_id)
     objects = relationship('Item',
+                           lazy='dynamic',
                            secondary='reference',
-                           backref='subject_item',
-                           foreign_keys=Reference.object_id)
+                           primaryjoin=id == Reference.subject_id,
+                           secondaryjoin=id == Reference.object_id)
     user = relationship('User', backref='items')
 
     __mapper_args__ = {