diff --git a/Data/Gettext.hs b/Data/Gettext.hs
--- a/Data/Gettext.hs
+++ b/Data/Gettext.hs
@@ -34,6 +34,7 @@
    gettext, cgettext,
    ngettext, cngettext,
    ngettext',
+   context,
    assocs,
    -- * Utilities for plural forms
    getHeaders,
@@ -51,7 +52,7 @@
 import qualified Data.ByteString.Lazy as L
 import qualified Data.Text.Lazy as T
 import qualified Data.Text.Lazy.Encoding as TLE
-import qualified Data.Trie as Trie
+import qualified Data.Map as M
 import Text.Printf
 
 import Data.Gettext.GmoFile
@@ -62,7 +63,7 @@
 data Catalog = Catalog {
   gmoSize :: Word32,
   gmoChoosePlural :: Int -> Int,
-  gmoData :: Trie.Trie [T.Text] }
+  gmoData :: M.Map B.ByteString [T.Text] }
 
 instance Show Catalog where
   show gmo = printf "<GetText data size=%d>" (gmoSize gmo)
@@ -76,20 +77,20 @@
 
 -- | Look up for string translation
 lookup :: B.ByteString -> Catalog -> Maybe [T.Text]
-lookup key gmo = Trie.lookup key (gmoData gmo)
+lookup key gmo = M.lookup key (gmoData gmo)
 
 -- | Get all translation pairs
 assocs :: Catalog -> [(B.ByteString, [T.Text])]
-assocs = Trie.toList . gmoData
+assocs = M.assocs . gmoData
 
 -- | Obtain headers of the catalog.
 -- Headers are defined as a translation for empty string.
 getHeaders :: Catalog -> Maybe Headers
 getHeaders gmo = getHeaders' (gmoData gmo)
 
-getHeaders' :: Trie.Trie [T.Text] -> Maybe Headers
+getHeaders' :: M.Map B.ByteString [T.Text] -> Maybe Headers
 getHeaders' trie =
-  case Trie.lookup "" trie of
+  case M.lookup "" trie of
     Nothing -> Nothing
     Just texts -> either error Just $ parseHeaders (head texts)
 
@@ -97,7 +98,7 @@
 getPluralDefinition :: Catalog -> Maybe (Int, Expr)
 getPluralDefinition gmo = getPluralDefinition' (gmoData gmo)
 
-getPluralDefinition' :: Trie.Trie [T.Text] -> Maybe (Int, Expr)
+getPluralDefinition' :: M.Map B.ByteString [T.Text] -> Maybe (Int, Expr)
 getPluralDefinition' trie =
   case getHeaders' trie of
     Nothing -> Nothing
@@ -159,11 +160,25 @@
                   else plural
       in  texts !! idx
 
+-- | Get sub-catalog for specific context
+context :: Catalog
+        -> B.ByteString -- ^ Context
+        -> Catalog
+context gmo ctxt =
+  let n = B.length ctxt + 1
+      prefix = ctxt `B.append` "\4"
+      trie =
+        M.fromList [(B.drop n key, value) | (key, value) <- M.assocs (gmoData gmo), prefix `B.isPrefixOf` key]
+  in  Catalog {
+        gmoSize = fromIntegral (M.size trie),
+        gmoChoosePlural = gmoChoosePlural gmo,
+        gmoData = trie }
+
 -- | Choose plural form index by number
 choosePluralForm :: Catalog -> Int -> Int
 choosePluralForm gmo = gmoChoosePlural gmo
 
-choosePluralForm' :: Trie.Trie [T.Text] -> Int -> Int
+choosePluralForm' :: M.Map B.ByteString [T.Text] -> Int -> Int
 choosePluralForm' trie n =
   case getPluralDefinition' trie of
     Nothing -> if n == 1 then 0 else 1 -- from GNU gettext implementation, known as 'germanic plural form'
@@ -186,5 +201,5 @@
     originals = map L.toStrict $ map getOrig fOriginals
     translations = map getTrans fTranslations
 
-    trie = Trie.fromList $ zip originals translations
+    trie = M.fromList $ zip originals translations
 
diff --git a/Setup.hs b/Setup.hs
deleted file mode 100644
--- a/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/examples/gmodump.hs b/examples/gmodump.hs
--- a/examples/gmodump.hs
+++ b/examples/gmodump.hs
@@ -2,9 +2,7 @@
 import Data.Gettext
 
 import Control.Monad
-import qualified Data.Trie as T
 import qualified Data.ByteString.Char8 as B8
-import qualified Data.ByteString.Lazy.Char8 as L8
 import qualified Data.Text.Lazy.IO as TLIO
 import System.Environment
 
diff --git a/haskell-gettext.cabal b/haskell-gettext.cabal
--- a/haskell-gettext.cabal
+++ b/haskell-gettext.cabal
@@ -1,5 +1,5 @@
 name:                haskell-gettext
-version:             0.1.1.0
+version:             0.1.2.0
 synopsis:            GetText runtime library implementation in pure Haskell
 description:         This package is pure Haskell implementation of GetText library runtime.
                      It allows you to:
@@ -48,7 +48,6 @@
                        binary >=0.7,
                        bytestring >=0.10,
                        text >= 1.2,
-                       bytestring-trie >=0.2,
                        containers >=0.5,
                        time >=1.4,
                        mtl >= 2.2.1,