diff --git a/relational-query/src/Database/Relational/Query/Constraint.hs b/relational-query/src/Database/Relational/Query/Constraint.hs
index b9e35cbc..b6028be5 100644
--- a/relational-query/src/Database/Relational/Query/Constraint.hs
+++ b/relational-query/src/Database/Relational/Query/Constraint.hs
@@ -1,7 +1,6 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE UndecidableInstances #-}
 
 -- |
 -- Module      : Database.Relational.Query.Constraint