diff --git a/geojson.cabal b/geojson.cabal
--- a/geojson.cabal
+++ b/geojson.cabal
@@ -1,5 +1,5 @@
 name:                   geojson
-version:                3.0.2
+version:                3.0.3
 license:                BSD3
 license-file:           LICENCE
 author:                 Dom De Re
@@ -27,7 +27,7 @@
 source-repository       this
     type:               git
     location:           https://github.com/indicatrix/hs-geojson.git
-    tag:                3.0.2
+    tag:                3.0.3
 
 library
     hs-source-dirs:     src
diff --git a/src/Data/SeqHelper.hs b/src/Data/SeqHelper.hs
--- a/src/Data/SeqHelper.hs
+++ b/src/Data/SeqHelper.hs
@@ -8,6 +8,7 @@
 module Data.SeqHelper (
   sequenceHead
   , sequenceTail
+  , unique
   ) where
 
 import qualified Data.Sequence as Sequence
@@ -23,3 +24,7 @@
 sequenceTail (_ Sequence.:<| tailS) = tailS
 sequenceTail _                      = Sequence.empty
 {-# INLINE sequenceTail #-}
+
+unique :: Eq a => Sequence.Seq a -> Sequence.Seq a
+unique Sequence.Empty      = Sequence.empty
+unique (x Sequence.:<| xs) = (Sequence.<|) x (unique (Sequence.filter (x /=) xs))