diff --git a/doc/cookbook/uverb/UVerb.lhs b/doc/cookbook/uverb/UVerb.lhs
index 52566ca2..cc771111 100644
--- a/doc/cookbook/uverb/UVerb.lhs
+++ b/doc/cookbook/uverb/UVerb.lhs
@@ -15,6 +15,7 @@ handlers that respond with arbitrary open unions of types.
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}