diff --git a/src/Text/Pandoc/Lua/Marshaling/List.hs b/src/Text/Pandoc/Lua/Marshaling/List.hs
index 57ccd4501..0b145d3a1 100644
--- a/src/Text/Pandoc/Lua/Marshaling/List.hs
+++ b/src/Text/Pandoc/Lua/Marshaling/List.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE DeriveDataTypeable    #-}
 {-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE FlexibleContexts      #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings     #-}
 {-# LANGUAGE UndecidableInstances  #-}