diff --git a/squeal-postgresql/src/Squeal/PostgreSQL/Session.hs b/squeal-postgresql/src/Squeal/PostgreSQL/Session.hs
index 9adf2324..051e9097 100644
--- a/squeal-postgresql/src/Squeal/PostgreSQL/Session.hs
+++ b/squeal-postgresql/src/Squeal/PostgreSQL/Session.hs
@@ -214,9 +214,9 @@ instance (Monad m, db0 ~ db1)
   return = pure
   (>>=) = flip pqBind
 
-instance (Monad m, db0 ~ db1)
+instance (MonadFail m, db0 ~ db1)
   => Fail.MonadFail (PQ db0 db1 m) where
-  fail = Fail.fail
+  fail = lift . Fail.fail
 
 instance db0 ~ db1 => MFunctor (PQ db0 db1) where
   hoist f (PQ pq) = PQ (f . pq)