diff --git a/language-ats.cabal b/language-ats.cabal
--- a/language-ats.cabal
+++ b/language-ats.cabal
@@ -1,5 +1,5 @@
 name:                language-ats
-version:             1.0.2.0
+version:             1.0.2.1
 synopsis:            Parser and pretty-printer for ATS.
 description:         Parser and pretty-printer for [ATS](http://www.ats-lang.org/), written with Happy and Alex.
 license:             BSD3
@@ -33,7 +33,7 @@
                      , lens
                      , deepseq
                      , ansi-wl-pprint >= 0.6.8
-                     , recursion-schemes
+                     , recursion-schemes >= 5.0.1
                      , composition-prelude
                      , ansi-terminal
                      , containers
diff --git a/src/Language/ATS.hs b/src/Language/ATS.hs
--- a/src/Language/ATS.hs
+++ b/src/Language/ATS.hs
@@ -25,6 +25,7 @@
                     , BinOp (..)
                     , DataPropLeaf (..)
                     , Leaf (..)
+                    , DataSortLeaf (..)
                     , Arg (..)
                     , Addendum (..)
                     , LambdaType (..)