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:             0.1.1.6
+version:             0.1.1.7
 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
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
@@ -553,6 +553,7 @@
       | eq { Equal }
       | mod { Mod }
       | percent { Mod }
+      | doubleBrackets { NotEq }
 
 -- | Optionally parse a function body
 OptExpression : { Nothing }
diff --git a/src/Language/ATS/PrettyPrint.hs b/src/Language/ATS/PrettyPrint.hs
--- a/src/Language/ATS/PrettyPrint.hs
+++ b/src/Language/ATS/PrettyPrint.hs
@@ -89,6 +89,7 @@
     pretty GreaterThanEq = ">="
     pretty StaticEq      = "=="
     pretty Mod           = "%"
+    pretty NotEq         = "<>"
 
 splits :: BinOp -> Bool
 splits Mult       = True
diff --git a/src/Language/ATS/Types.hs b/src/Language/ATS/Types.hs
--- a/src/Language/ATS/Types.hs
+++ b/src/Language/ATS/Types.hs
@@ -222,6 +222,7 @@
            | LogicalOr
            | StaticEq
            | Mod
+           | NotEq
            deriving (Show, Eq, Generic, NFData)
 
 -- FIXME add position information?