diff --git a/Data/Library.hs b/Data/Library.hs
--- a/Data/Library.hs
+++ b/Data/Library.hs
@@ -4,6 +4,7 @@
 , ItemId
 , LibraryItem(..)
 , Error(..)
+, empty
 , move
 , copy
 , delete
@@ -18,7 +19,7 @@
 
 where
 import Data.Text (Text)
-import Data.IntSet (IntSet, insert, empty)
+import Data.IntSet (IntSet, insert)
 import qualified Data.IntSet as IS
 import Data.Sequence (Seq, (|>))
 import qualified Data.Sequence as Seq
@@ -40,6 +41,9 @@
 
 type ItemId = Int
 
+empty :: Library
+empty = Seq.empty
+
 move :: Library -> ItemId -> ItemId -> UTCTime -> Either Error Library 
 move lib origin destination t = if origin == 0 then Left MovingRoot else do
     d <- getItem destination lib    -- destination
@@ -98,7 +102,7 @@
     where
         i = Item (Seq.length lib) (fromText name) (fmap fromText description) 
                  creationTime creationTime parent $ 
-                 maybe (Left $ Dir empty empty) Right uuiri
+                 maybe (Left $ Dir IS.empty IS.empty) Right uuiri
 
 -- | No bounds checking and doesn't filter deleted items
 -- returns an exception error when the item is not found
@@ -158,7 +162,7 @@
     , f1 t, d1 t
     ]
 f1 t = Item 1 "f1" (Just "ficheiro 1") t t 0 (Right $ toUUIRI (UUID $ fromWords 1 2 3 4) "http://blah.com/f1.txt")
-d1 t = Item 2 "d1" (Just "dir 1") t t 0 (Left (empty, empty))
+d1 t = Item 2 "d1" (Just "dir 1") t t 0 (Left (IS.empty, IS.empty))
 -}
 
 instance ToJSON LibraryItem where
diff --git a/Data/Library/IRI.hs b/Data/Library/IRI.hs
--- a/Data/Library/IRI.hs
+++ b/Data/Library/IRI.hs
@@ -23,7 +23,6 @@
 data IRI = Relative Text
          | Absolute Text
          deriving(Show)
-deriveSafeCopy 0 'base ''IRI -- from Data.SafeCopy
 
 instance ToJSON IRI where
     toJSON = toJSON . fromIRI
@@ -65,3 +64,4 @@
 dirs (Relative t) = split (== '/') t
 dirs (Absolute t) = drop 3 $ split (== '/') t
 
+$(deriveSafeCopy 0 'base ''IRI) 
diff --git a/dirfiles.cabal b/dirfiles.cabal
--- a/dirfiles.cabal
+++ b/dirfiles.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                dirfiles
-version:             0.1.0.3
+version:             0.1.0.4
 -- synopsis:            
 description:         Simple datatype to represent a library with files and folders
 license:             BSD3