diff --git a/nova/db/sqlalchemy/models.py b/nova/db/sqlalchemy/models.py
index fa10356a6ff0..b956ea6068e5 100644
--- a/nova/db/sqlalchemy/models.py
+++ b/nova/db/sqlalchemy/models.py
@@ -465,9 +465,11 @@ class Reservation(BASE, NovaBase):
     uuid = Column(String(36), nullable=False)
 
     usage_id = Column(Integer, ForeignKey('quota_usages.id'), nullable=False)
+    # NOTE(dprince): Force innerjoin below for lockmode update on PostgreSQL
     usage = relationship(QuotaUsage,
                          backref=backref('reservations'),
                          foreign_keys=usage_id,
+                         innerjoin=True,
                          primaryjoin='and_('
                               'Reservation.usage_id == QuotaUsage.id,'
                               'Reservation.deleted == False)')