diff --git a/Network/Wai/Handler/SCGI.hs b/Network/Wai/Handler/SCGI.hs
--- a/Network/Wai/Handler/SCGI.hs
+++ b/Network/Wai/Handler/SCGI.hs
@@ -5,11 +5,11 @@
     ) where
 
 import Network.Wai
-import Network.Wai.Handler.CGI (run'')
-import Network.Wai.Handler.Helper (requestBodyFunc)
+import Network.Wai.Handler.CGI (run'', requestBodyFunc)
 import Foreign.Ptr
 import Foreign.Marshal.Alloc
 import Foreign.C
+import Data.ByteString (ByteString)
 import qualified Data.ByteString as S
 import qualified Data.ByteString.Unsafe as S
 import qualified Data.ByteString.Char8 as S8
@@ -19,10 +19,10 @@
 run :: Application -> IO ()
 run app = runOne Nothing app >> run app
 
-runSendfile :: String -> Application -> IO ()
+runSendfile :: ByteString -> Application -> IO ()
 runSendfile sf app = runOne (Just sf) app >> runSendfile sf app
 
-runOne :: Maybe String -> Application -> IO ()
+runOne :: Maybe ByteString -> Application -> IO ()
 runOne sf app = do
     socket <- c'accept 0 nullPtr nullPtr
     headersBS <- readNetstring socket
diff --git a/wai-handler-scgi.cabal b/wai-handler-scgi.cabal
--- a/wai-handler-scgi.cabal
+++ b/wai-handler-scgi.cabal
@@ -1,5 +1,5 @@
 name:            wai-handler-scgi
-version:         0.2.0
+version:         0.3.0
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -12,10 +12,10 @@
 homepage:        http://github.com/snoyberg/wai-handler-scgi
 
 library
-    build-depends:   base >= 4 && < 5,
-                     wai >= 0.2.0 && < 0.3.0,
-                     wai-extra >= 0.2.1 && < 0.3.0,
-                     bytestring >= 0.9.1.4 && < 0.10
+    build-depends:   base                >= 4           && < 5
+                   , wai                 >= 0.3         && < 0.4
+                   , wai-extra           >= 0.3         && < 0.4
+                   , bytestring          >= 0.9.1.4     && < 0.10
     exposed-modules: Network.Wai.Handler.SCGI
     ghc-options:     -Wall