diff --git a/rattail_tempmon/db/model.py b/rattail_tempmon/db/model.py
index ba7e63a..b3e1ece 100644
--- a/rattail_tempmon/db/model.py
+++ b/rattail_tempmon/db/model.py
@@ -135,7 +135,10 @@ class Reading(Base):
         Client,
         doc="""
         Reference to the tempmon client which took this reading.
-        """)
+        """,
+        backref=orm.backref(
+            'readings',
+            cascade='all, delete-orphan'))
 
     probe_uuid = sa.Column(sa.String(length=32), nullable=False)
     probe = orm.relationship(