diff --git a/depicts/model.py b/depicts/model.py
index b23c3c1..3c92751 100644
--- a/depicts/model.py
+++ b/depicts/model.py
@@ -105,10 +105,14 @@ class Item(Base):
 
 class Triple(Base):
     __tablename__ = 'triple'
-    subject_id = Column(Integer, primary_key=True)
+    subject_id = Column(Integer,
+                        ForeignKey('item.item_id'),
+                        primary_key=True)
     predicate_id = Column(Integer, primary_key=True, index=True)
     object_id = Column(Integer, primary_key=True, index=True)
 
+    subject = relationship('Item', backref='triples')
+
 class HumanItem(Base):
     __tablename__ = 'human'
     item_id = Column(Integer, primary_key=True, autoincrement=False)