diff --git a/src/Graphics/ThumbnailPlus/ImageSize.hs b/src/Graphics/ThumbnailPlus/ImageSize.hs
--- a/src/Graphics/ThumbnailPlus/ImageSize.hs
+++ b/src/Graphics/ThumbnailPlus/ImageSize.hs
@@ -1,110 +1,7 @@
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE DeriveDataTypeable #-}
--- | Detect the image size without opening the image itself.
---
--- Amazingly, reimplementing this wheel is the recommended way of
--- not processing huge images according to gd's FAQ.  We hope to
--- be at least as restrictive as gd itself is, otherwise some
--- malicious image could get past this code and blow on gd's
--- hand.
---
--- This code has been ressurected by the now-deprecated
--- @imagesize-conduit@ library by Michael Snoyman.
 module Graphics.ThumbnailPlus.ImageSize
   ( Size (..)
   , FileFormat (..)
   , sinkImageInfo
   ) where
 
-import qualified Data.ByteString.Lazy as L
-import Data.Conduit
-import qualified Data.Conduit.Binary as CB
-import qualified Data.ByteString as S
-import Data.ByteString.Char8 ()
-import Data.ByteString.Lazy.Char8 ()
-import qualified Data.Typeable as T
-import Control.Applicative ((<$>), (<*>))
-
-
-data Size = Size { width :: Int, height :: Int }
-  deriving (Show, Eq, Ord, Read, T.Typeable)
-
-
-data FileFormat = GIF | PNG | JPG
-  deriving (Show, Eq, Ord, Read, Enum, T.Typeable)
-
-
--- | Find out the size of an image.  Also returns the file format
--- that parsed correctly.  Note that this function does not
--- verify that the file is indeed in the format that it returns,
--- since it looks only at a small part of the header.
-sinkImageInfo :: Monad m => Consumer S.ByteString m (Maybe (Size, FileFormat))
-sinkImageInfo = start id
-  where
-    start front = await >>= maybe (return Nothing) (pushHeader front)
-
-    pushHeader front bs'
-      | S.length bs >= 11 && S.take 5 (S.drop 6 bs) ==
-        S.pack [0x4A, 0x46, 0x49, 0x46, 0x00] =
-          leftover (S.drop 4 bs) >> jpg
-      | S.length bs >= 6 && S.take 6 bs `elem` gifs =
-        leftover (S.drop 6 bs) >> gif
-      | S.length bs >= 8 && S.take 8 bs == S.pack [137, 80, 78, 71, 13, 10, 26, 10] =
-        leftover (S.drop 8 bs) >> png
-      | S.length bs < 11 = start $ S.append bs
-      | otherwise = leftover bs >> return Nothing
-      where
-      bs = front bs'
-
-    gifs = ["GIF87a", "GIF89a"]
-    gif = do
-      b <- CB.take 4
-      let go x y = fromIntegral x + (fromIntegral y) * 256
-      return $ case L.unpack b of
-        [w1, w2, h1, h2] -> Just (Size (go w1 w2) (go h1 h2), GIF)
-        _ -> Nothing
-
-    png = do
-      CB.drop 4
-      hdr <- CB.take 4
-      if hdr == "IHDR"
-        then do
-          mw <- getInt 4 0
-          mh <- getInt 4 0
-          return $ (\w h -> (Size w h, PNG)) <$> mw <*> mh
-        else return Nothing
-
-    jpg = do
-      mi <- getInt 2 0
-      case mi of
-        Nothing -> return Nothing
-        Just i -> do
-          CB.drop $ i - 2
-          jpgFrame
-
-    jpgFrame = do
-      mx <- CB.head
-      case mx of
-        Just 255 -> do
-          my <- CB.head
-          case my of
-            Just 0xC0 -> do
-              _  <- CB.take 3
-              mh <- getInt 2 0
-              mw <- getInt 2 0
-              return $ (\w h -> (Size w h, JPG)) <$> mw <*> mh
-            Just _ -> jpg
-            Nothing -> return Nothing
-        _ -> return Nothing
-
-getInt :: (Monad m, Integral i)
-     => Int
-     -> i
-     -> Consumer S.ByteString m (Maybe i)
-getInt 0 i = return $ Just i
-getInt len i = do
-  mx <- CB.head
-  case mx of
-    Nothing -> return Nothing
-    Just x -> getInt (len - 1) (i * 256 + fromIntegral x)
+import Data.Conduit.ImageSize
diff --git a/tests/Main.hs b/tests/Main.hs
--- a/tests/Main.hs
+++ b/tests/Main.hs
@@ -54,7 +54,7 @@
 
 check :: Maybe (TP.Size, TP.FileFormat) -> FilePath -> Expectation
 check ex fp = do
-  size <- C.runResourceT $ CB.sourceFile fp C.$$ TPIS.sinkImageInfo
+  size <- R.runResourceT $ CB.sourceFile fp C.$$ TPIS.sinkImageInfo
   size `shouldBe` ex
 
 checkThumbnail :: TP.Thumbnail -> Expectation
diff --git a/thumbnail-plus.cabal b/thumbnail-plus.cabal
--- a/thumbnail-plus.cabal
+++ b/thumbnail-plus.cabal
@@ -1,5 +1,5 @@
 name:                thumbnail-plus
-version:             1.0.3
+version:             1.0.4
 synopsis:            Generate thumbnails easily and safely.
 homepage:            https://github.com/prowdsponsor/thumbnail-plus
 license:             MIT
@@ -23,8 +23,8 @@
    * File sizes are constrained and checked.
   .
    * Image sizes are constrained and checked before the images
-     are loaded into memory.  Uses code from the deprecated
-     @imagesize-conduit@ by Michael Snoyman.
+     are loaded into memory.  Uses @imagesize-conduit@ by Michael
+     Snoyman.
   .
    * Optionally, the original image is reencoded before being
      saved.
@@ -45,21 +45,22 @@
     Graphics.ThumbnailPlus
     Graphics.ThumbnailPlus.ImageSize
   build-depends:
-    base          >= 4.6   && < 5,
-    bytestring    >= 0.10,
-    data-default  >= 0.5,
+    base              >= 4.6   && < 5,
+    bytestring        >= 0.10,
+    data-default      >= 0.5,
 
-    transformers  >= 0.3,
-    either        >= 4.1,
+    transformers      >= 0.3,
+    either            >= 4.1,
 
-    conduit       >= 1.1,
-    conduit-extra >= 1.1,
-    resourcet     >= 0.4,
+    conduit           >= 1.1,
+    conduit-extra     >= 1.1,
+    resourcet         >= 0.4,
+    imagesize-conduit >= 1.0.0.3,
 
     directory,
-    temporary     >= 1.2,
+    temporary         >= 1.2,
 
-    gd            >= 3000.7.3
+    gd                >= 3000.7.3
   hs-source-dirs:      src
   default-language:    Haskell2010
   ghc-options:         -Wall
@@ -71,6 +72,7 @@
     data-default,
     transformers,
     conduit,
+    conduit-extra,
     resourcet,
     directory,