diff --git a/haskell-experiments/src/Datalog/NaiveDatabase.hs b/haskell-experiments/src/Datalog/NaiveDatabase.hs
index ba12d09..178c016 100644
--- a/haskell-experiments/src/Datalog/NaiveDatabase.hs
+++ b/haskell-experiments/src/Datalog/NaiveDatabase.hs
@@ -40,7 +40,7 @@ instance DatalogDB NaiveDatabase where
   -- insertRelation :: NaiveDatabase -> Text -> Relation -> NaiveDatabase
   -- insertRelation = _
 
-lookupRelation0 :: RelationId -> NaiveDatabase -> Int -> Set [Term] -> Relation
+lookupRelation0 :: DatalogDB db => Text -> db -> Int -> Set [Constant] -> Relation
 lookupRelation0 relationName db newArity tuples =
   case lookupRelation db relationName of
     Nothing -> Relation relationName newArity tuples []