diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 3.0.9.1
+
+Add support for blaze-builder 0.4
+
 ## 3.0.9
 
 * Add runEnv: like run but uses $PORT [#334](https://github.com/yesodweb/wai/pull/334)
diff --git a/Network/Wai/Handler/Warp/Buffer.hs b/Network/Wai/Handler/Warp/Buffer.hs
--- a/Network/Wai/Handler/Warp/Buffer.hs
+++ b/Network/Wai/Handler/Warp/Buffer.hs
@@ -1,6 +1,6 @@
 module Network.Wai.Handler.Warp.Buffer where
 
-import qualified Blaze.ByteString.Builder.Internal.Buffer as B (Buffer (..))
+import qualified Data.Streaming.ByteString.Builder.Buffer as B (Buffer (..))
 import Data.Word (Word8)
 import Foreign.ForeignPtr (newForeignPtr_)
 import Foreign.Marshal.Alloc (mallocBytes, free)
diff --git a/Network/Wai/Handler/Warp/IO.hs b/Network/Wai/Handler/Warp/IO.hs
--- a/Network/Wai/Handler/Warp/IO.hs
+++ b/Network/Wai/Handler/Warp/IO.hs
@@ -1,14 +1,47 @@
 {-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP #-}
 
 module Network.Wai.Handler.Warp.IO where
 
-import Blaze.ByteString.Builder.Internal.Types (Builder(..), BuildSignal(..), BufRange(..), runBuildStep, buildStep)
 import Data.ByteString.Internal (ByteString(..))
 import Foreign.ForeignPtr (newForeignPtr_)
-import Foreign.Ptr (plusPtr, minusPtr)
 import Network.Wai.Handler.Warp.Buffer
 
+-- Support for doctest, where cabal macros are not available
+#ifndef MIN_VERSION_blaze_builder
+#define MIN_VERSION_blaze_builder(x, y, z) 1
+#endif
+
+#if MIN_VERSION_blaze_builder(0,4,0)
+
+import Blaze.ByteString.Builder (Builder)
+import Data.ByteString.Builder.Extra (runBuilder, Next(Done, More, Chunk))
+
 toBufIOWith :: Buffer -> BufSize -> (ByteString -> IO ()) -> Builder -> IO ()
+toBufIOWith buf !size io builder = loop firstWriter
+  where
+    firstWriter = runBuilder builder
+    runIO len = toBS buf len >>= io
+    loop writer = do
+        (len, signal) <- writer buf size
+        case signal of
+             Done -> runIO len
+             More minSize next
+               | size < minSize -> error "toBufIOWith: BufferFull: minSize"
+               | otherwise      -> do
+                   runIO len
+                   loop next
+             Chunk bs next -> do
+                 runIO len
+                 io bs
+                 loop next
+
+#else /* !MIN_VERSION_blaze_builder(0,4,0) */
+
+import Blaze.ByteString.Builder.Internal.Types (Builder(..), BuildSignal(..), BufRange(..), runBuildStep, buildStep)
+import Foreign.Ptr (plusPtr, minusPtr)
+
+toBufIOWith :: Buffer -> BufSize -> (ByteString -> IO ()) -> Builder -> IO ()
 toBufIOWith buf !size io (Builder build) = loop firstStep
   where
     firstStep = build (buildStep finalStep)
@@ -28,6 +61,8 @@
                  runIO ptr
                  io bs
                  loop next
+
+#endif /* !MIN_VERSION_blaze_builder(0,4,0) */
 
 toBS :: Buffer -> Int -> IO ByteString
 toBS ptr siz = do
diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             3.0.9
+Version:             3.0.9.1
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             MIT
 License-file:        LICENSE
@@ -30,7 +30,7 @@
   Build-Depends:     base                      >= 3        && < 5
                    , array
                    , auto-update               >= 0.1.1    && < 0.2
-                   , blaze-builder             >= 0.3.3  && < 0.4
+                   , blaze-builder             >= 0.3.3    && < 0.5
                    , bytestring                >= 0.9.1.4
                    , case-insensitive          >= 0.2
                    , ghc-prim
@@ -41,7 +41,7 @@
                    , void
                    , wai                       >= 3.0      && < 3.1
                    , text
-                   , streaming-commons         >= 0.1.2
+                   , streaming-commons         >= 0.1.10
   if flag(network-bytestring)
       Build-Depends: network                   >= 2.2.1.5  && < 2.2.3
                    , network-bytestring        >= 0.1.3    && < 0.1.4
@@ -112,7 +112,7 @@
     Build-Depends:   base >= 4 && < 5
                    , array
                    , auto-update
-                   , blaze-builder             >= 0.3.3    && < 0.4
+                   , blaze-builder             >= 0.3.3    && < 0.5
                    , bytestring                >= 0.9.1.4
                    , case-insensitive          >= 0.2
                    , ghc-prim
@@ -132,7 +132,7 @@
                    , time
                    , old-locale
                    , text
-                   , streaming-commons >= 0.1.1
+                   , streaming-commons         >= 0.1.10
                    , async
 
   if (os(linux) || os(freebsd) || os(darwin)) && flag(allow-sendfilefd)