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:             0.1.0.4
+version:             0.1.0.5
 synopsis:            Parser and pretty-printer for ATS.
 description:         Parser and pretty-printer for [ATS](http://www.ats-lang.org/), written with Happy and Alex.
 homepage:            https://github.com/vmchale/language-ats#readme
diff --git a/src/Language/ATS/Parser.y b/src/Language/ATS/Parser.y
--- a/src/Language/ATS/Parser.y
+++ b/src/Language/ATS/Parser.y
@@ -621,6 +621,7 @@
          | stadef boolLit eq Name { Stadef (over _head toLower (show $2)) $4 [] } -- TODO identifierSpace
          | sortdef IdentifierOr eq Type { SortDef $1 $2 $4 }
          | AndSort { $1 }
+         | vtypedef IdentifierOr eq Leaves {% Left $ Expected $3 "Type" "|" }
 
 Fixity : infixr { RightFix $1 }
        | infixl { LeftFix $1 }