diff --git a/filesystem-trees.cabal b/filesystem-trees.cabal
--- a/filesystem-trees.cabal
+++ b/filesystem-trees.cabal
@@ -1,5 +1,5 @@
 Name: filesystem-trees
-Version: 0.1
+Version: 0.1.0.1
 Synopsis: Recursively manipulate and traverse filesystems as lazy rose trees.
 Cabal-Version: >= 1.10
 License: BSD3
@@ -24,4 +24,5 @@
                  , dlist >= 0.2 && < 1.0
                  , mtl >= 1.0 && < 3.0
                  , cond >= 0.3 && < 0.5
+                 , deepseq >= 1.1 && < 1.5
   exposed-modules: System.File.Tree
diff --git a/src/System/File/Tree.hs b/src/System/File/Tree.hs
--- a/src/System/File/Tree.hs
+++ b/src/System/File/Tree.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE GeneralizedNewtypeDeriving, DeriveDataTypeable, 
+{-# LANGUAGE CPP, GeneralizedNewtypeDeriving, DeriveDataTypeable, 
              FlexibleInstances, MultiParamTypeClasses, FunctionalDependencies,
              TypeSynonymInstances, RankNTypes
   #-}
@@ -22,7 +22,7 @@
        , remove, tryRemove, tryRemoveWith              
          -- * Operations on directory trees
          -- **basic operations
-       , pop, pop_, flatten, flattenPostOrder
+       , pop, pop_, flatten, flattenPostOrder, levels
          -- ** map over subtrees
        , map, mapM, mapM_
          -- **find subtrees
@@ -50,10 +50,11 @@
 import System.Posix.Files (getSymbolicLinkStatus, isSymbolicLink)
 
 import Data.Tree (Tree(..), Forest)
-import qualified Data.Tree as Tree (flatten)
+import qualified Data.Tree as Tree (flatten, levels)
 import Data.DList as DL (DList(..), cons, append, toList, empty, concat, snoc)
 
 import Control.Exception (throwIO, catch, IOException)
+import System.IO.Error (ioeGetErrorType, doesNotExistErrorType)
 import Control.Monad (forM, liftM, liftM2, void)
 import Control.Monad.Identity (runIdentity)
 import Control.Applicative ((<$>), (<*>), (<*))
@@ -63,8 +64,10 @@
 import Data.Maybe (mapMaybe, catMaybes)
 import Data.Function (on)
 import Data.Lens.Common (Lens, lens, getL, setL, modL)
+import Control.DeepSeq (NFData(..), deepseq)
 import Control.Conditional (ifM, (<&&>), (<||>), notM, condM, otherwiseM)
 
+
 import Data.Word (Word)
 import Data.Typeable (Typeable)
 import Data.Data (Data)
@@ -112,6 +115,9 @@
 newtype FSTree = FSTree { toTree :: Tree FilePath } deriving 
                 (Typeable, Data, Eq, Read, Show)
 
+instance NFData FSTree where
+  rnf t = getL label t `deepseq` rnf (getL children t)
+
 type FSForest = [FSTree]
 
 -- |A pseudo-constructor for 'FSTree'.
@@ -179,9 +185,19 @@
 isDir :: FilePath -> IO Bool
 isDir = doesDirectoryExist
 
--- |Checks if a path refers to a symbolic link
+-- |Checks if a path refers to a symbolic link.
+-- NOTE: always returns False on Windows
 isSymLink :: FilePath -> IO Bool
-isSymLink p = isSymbolicLink <$> getSymbolicLinkStatus p
+#if CABAL_OS_WINDOWS
+isSymLink p = return False
+#else
+isSymLink p = (isSymbolicLink <$> getSymbolicLinkStatus p)
+              `catch` handler
+  where handler :: IOError -> IO Bool 
+        handler e
+          | ioeGetErrorType e == doesNotExistErrorType = return False
+          | otherwise = throwIO e
+#endif
 
 -- |Checks if a path refers to a symbolically linked directory 
 isSymDir :: FilePath -> IO Bool
@@ -222,6 +238,10 @@
 flattenPostOrder = toList . flatten' . prependPaths
   where flatten' (Node p cs) = DL.concat (P.map flatten' cs) `snoc` p  
 
+-- |List of file paths at each level of the tree.
+levels :: FSTree -> [[FilePath]]
+levels = Tree.levels . prependPaths
+
 -- |Applies a function over the filepaths of a directory tree. 
 --
 -- Because we can't guarantee that the internal 'FSTree' representation is preserved 
@@ -247,11 +267,10 @@
 find :: (FilePath -> Bool) -> FSForest -> FSForest
 find p = snd . extract p
 
--- |A generalization of 'find'. The first element of the result 
--- represents the forest after removing all subtrees that match the given predicate, 
--- and the second element is a list of trees that matched. This could be useful if 
--- you want to handle certain directories specially from others within a 
--- sub-filesystem.
+-- |The first element of the result represents the forest after removing all 
+-- subtrees that match the given predicate, and the second element is a list of 
+-- trees that matched. This could be useful if you want to handle certain 
+-- directories specially from others within a sub-filesystem.
 extract :: (FilePath -> Bool) -> FSForest -> (FSForest, FSForest)
 extract p = runIdentity . extractM (return . p)
 
@@ -341,8 +360,7 @@
         ]
   zipWithDestM_
     (\s d -> ifM (isRealDir s) 
-             (do tryRemoveDirectory s
-                 createDirectory d)
+             (createDirectory d)
              (renameFile s d)
     )
     dest fs