diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 3.1.2
+
+* Configurable Slowloris size [#418](https://github.com/yesodweb/wai/pull/418)
+
 ## 3.1.0
 
 * Supporting HTTP/2 [#399](https://github.com/yesodweb/wai/pull/399)
diff --git a/Network/Wai/Handler/Warp.hs b/Network/Wai/Handler/Warp.hs
--- a/Network/Wai/Handler/Warp.hs
+++ b/Network/Wai/Handler/Warp.hs
@@ -64,6 +64,7 @@
   , setProxyProtocolNone
   , setProxyProtocolRequired
   , setProxyProtocolOptional
+  , setSlowlorisSize
     -- ** Getters
   , getPort
   , getHost
@@ -337,6 +338,12 @@
 -- Since 3.0.5
 setProxyProtocolOptional :: Settings -> Settings
 setProxyProtocolOptional y = y { settingsProxyProtocol = ProxyProtocolOptional }
+
+-- | Size in bytes read to prevent Slowloris protection. Default value: 2048
+--
+-- Since 3.1.2
+setSlowlorisSize :: Int -> Settings -> Settings
+setSlowlorisSize x y = y { settingsSlowlorisSize = x }
 
 -- | Explicitly pause the slowloris timeout.
 --
diff --git a/Network/Wai/Handler/Warp/HTTP2/Sender.hs b/Network/Wai/Handler/Warp/HTTP2/Sender.hs
--- a/Network/Wai/Handler/Warp/HTTP2/Sender.hs
+++ b/Network/Wai/Handler/Warp/HTTP2/Sender.hs
@@ -10,7 +10,7 @@
 import Control.Concurrent (forkIO)
 import Control.Concurrent.STM
 import qualified Control.Exception as E
-import Control.Monad (void, unless)
+import Control.Monad (unless, void, when)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Builder.Extra as B
 import Foreign.Ptr
@@ -111,27 +111,44 @@
             case aux of
                 Oneshot True -> do -- hasBody
                     -- Data frame payload
-                    off <- sendHeadersIfNecessary total
-                    Next datPayloadLen mnext <- fillResponseBodyGetNext conn ii off lim rsp
-                    fillDataHeaderSend strm total datPayloadLen mnext pri
+                    (off, _) <- sendHeadersIfNecessary total
+                    let payloadOff = off + frameHeaderLength
+                    Next datPayloadLen mnext <-
+                        fillResponseBodyGetNext conn ii payloadOff lim rsp
+                    fillDataHeaderSend strm total datPayloadLen mnext
+                    maybeEnqueueNext strm mnext pri
                 Oneshot False -> do
                     -- "closed" must be before "connSendAll". If not,
                     -- the context would be switched to the receiver,
                     -- resulting the inconsistency of concurrency.
                     closed ctx strm Finished
-                    bufferIO connWriteBuffer total connSendAll
+                    flushN total
                 Persist sq tvar -> do
-                    off <- sendHeadersIfNecessary total
-                    Next datPayloadLen mnext <- fillStreamBodyGetNext conn off lim sq tvar
-                    fillDataHeaderSend strm total datPayloadLen mnext pri
+                    (off, needSend) <- sendHeadersIfNecessary total
+                    let payloadOff = off + frameHeaderLength
+                    Next datPayloadLen mnext <-
+                        fillStreamBodyGetNext conn payloadOff lim sq tvar
+                    -- If no data was immediately available, avoid sending an
+                    -- empty data frame.
+                    if datPayloadLen > 0 then
+                        fillDataHeaderSend strm total datPayloadLen mnext
+                      else
+                        when needSend $ flushN off
+                    maybeEnqueueNext strm mnext pri
         loop
     switch out@(ONext strm curr) pri = unlessClosed ctx conn strm $ do
         checkWindowSize connectionWindow (streamWindow strm) outputQ out pri $ \lim -> do
             -- Data frame payload
             Next datPayloadLen mnext <- curr lim
-            fillDataHeaderSend strm 0 datPayloadLen mnext pri
+            fillDataHeaderSend strm 0 datPayloadLen mnext
+            maybeEnqueueNext strm mnext pri
         loop
 
+    -- Flush the connection buffer to the socket, where the first 'n' bytes of
+    -- the buffer are filled.
+    flushN :: Int -> IO ()
+    flushN n = bufferIO connWriteBuffer n connSendAll
+
     headerContinue sid rsp endOfStream = do
         builder <- hpackEncodeHeader ctx ii settings rsp
         (len, signal) <- B.runBuilder builder bufHeaderPayload headerPayloadLim
@@ -144,8 +161,7 @@
 
     continue _   len B.Done = return len
     continue sid len (B.More _ writer) = do
-        let total = len + frameHeaderLength
-        bufferIO connWriteBuffer total connSendAll
+        flushN $ len + frameHeaderLength
         (len', signal') <- writer bufHeaderPayload headerPayloadLim
         let flag = case signal' of
                 B.Done -> setEndHeader defaultFlags
@@ -153,8 +169,7 @@
         fillFrameHeader FrameContinuation len' sid flag connWriteBuffer
         continue sid len' signal'
     continue sid len (B.Chunk bs writer) = do
-        let total = len + frameHeaderLength
-        bufferIO connWriteBuffer total connSendAll
+        flushN $ len + frameHeaderLength
         let (bs1,bs2) = BS.splitAt headerPayloadLim bs
             len' = BS.length bs1
         void $ copy bufHeaderPayload bs1
@@ -164,15 +179,28 @@
           else
             continue sid len' (B.Chunk bs2 writer)
 
-    sendHeadersIfNecessary total = do
-        let datPayloadOff = total + frameHeaderLength
-        if datPayloadOff < connBufferSize then
-            return datPayloadOff
-          else do
-            bufferIO connWriteBuffer total connSendAll
-            return frameHeaderLength
+    -- True if the connection buffer has room for a 1-byte data frame.
+    canFitDataFrame total = total + frameHeaderLength < connBufferSize
 
-    fillDataHeaderSend strm otherLen datPayloadLen mnext pri = do
+    -- Re-enqueue the stream in the output queue if more output is immediately
+    -- available; do nothing otherwise.  If the stream is not finished, it must
+    -- already have been written to the 'TVar' owned by 'waiter', which will
+    -- put it back into the queue when more output becomes available.
+    maybeEnqueueNext :: Stream -> Control DynaNext -> Priority -> IO ()
+    maybeEnqueueNext strm (CNext next) = enqueue outputQ (ONext strm next)
+    maybeEnqueueNext _    _            = const $ return ()
+
+
+    -- Send headers if there is not room for a 1-byte data frame, and return
+    -- the offset of the next frame's first header byte and whether the headers
+    -- still need to be sent.
+    sendHeadersIfNecessary total
+      | canFitDataFrame total = return (total, True)
+      | otherwise             = do
+          flushN total
+          return (0, False)
+
+    fillDataHeaderSend strm otherLen datPayloadLen mnext = do
         -- Data frame header
         let sid = streamNumber strm
             buf = connWriteBuffer `plusPtr` otherLen
@@ -187,14 +215,10 @@
         case mnext of
             CFinish    -> closed ctx strm Finished
             _          -> return ()
-        bufferIO connWriteBuffer total connSendAll
+        flushN total
         atomically $ do
            modifyTVar' connectionWindow (subtract datPayloadLen)
            modifyTVar' (streamWindow strm) (subtract datPayloadLen)
-        case mnext of
-            CFinish    -> return ()
-            CNext next -> enqueue outputQ (ONext strm next) pri
-            CNone      -> return ()
 
     fillFrameHeader ftyp len sid flag buf = encodeFrameHeaderBuf ftyp hinfo buf
       where
diff --git a/Network/Wai/Handler/Warp/Internal.hs b/Network/Wai/Handler/Warp/Internal.hs
--- a/Network/Wai/Handler/Warp/Internal.hs
+++ b/Network/Wai/Handler/Warp/Internal.hs
@@ -45,8 +45,8 @@
     --
     -- * When all request headers are read, the timeout is tickled.
     --
-    -- * Every time at least 2048 bytes of the request body are read, the timeout
-    --   is tickled.
+    -- * Every time at least the slowloris size settings number of bytes of the request
+    --   body are read, the timeout is tickled.
     --
     -- * The timeout is paused while executing user code. This will apply to both
     --   the application itself, and a ResponseSource response. The timeout is
diff --git a/Network/Wai/Handler/Warp/Run.hs b/Network/Wai/Handler/Warp/Run.hs
--- a/Network/Wai/Handler/Warp/Run.hs
+++ b/Network/Wai/Handler/Warp/Run.hs
@@ -314,7 +314,7 @@
         http2 conn ii origAddr transport settings recvN app
       else do
         istatus <- newIORef False
-        src <- mkSource (wrappedRecv conn th istatus)
+        src <- mkSource (wrappedRecv conn th istatus (settingsSlowlorisSize settings))
         writeIORef istatus True
         leftoverSource src bs
         addr <- getProxyProtocolAddr src
@@ -470,12 +470,12 @@
                 | toRead' >= 0 -> loop toRead'
                 | otherwise -> return False
 
-wrappedRecv :: Connection -> T.Handle -> IORef Bool -> IO ByteString
-wrappedRecv Connection { connRecv = recv } th istatus = do
+wrappedRecv :: Connection -> T.Handle -> IORef Bool -> Int -> IO ByteString
+wrappedRecv Connection { connRecv = recv } th istatus slowlorisSize = do
     bs <- recv
     unless (S.null bs) $ do
         writeIORef istatus True
-        when (S.length bs >= 2048) $ T.tickle th
+        when (S.length bs >= slowlorisSize) $ T.tickle th
     return bs
 
 -- Copied from: https://github.com/mzero/plush/blob/master/src/Plush/Server/Warp.hs
diff --git a/Network/Wai/Handler/Warp/Settings.hs b/Network/Wai/Handler/Warp/Settings.hs
--- a/Network/Wai/Handler/Warp/Settings.hs
+++ b/Network/Wai/Handler/Warp/Settings.hs
@@ -89,6 +89,10 @@
       -- ^ Specify usage of the PROXY protocol.
       --
       -- Since 3.0.5.
+    , settingsSlowlorisSize :: Int
+      -- ^ Size of bytes read to prevent Slowloris protection. Default value: 2048
+      --
+      -- Since 3.1.2.
     }
 
 -- | Specify usage of the PROXY protocol.
@@ -119,6 +123,7 @@
     , settingsServerName = S8.pack $ "Warp/" ++ showVersion Paths_warp.version
     , settingsMaximumBodyFlush = Just 8192
     , settingsProxyProtocol = ProxyProtocolNone
+    , settingsSlowlorisSize = 2048
     }
 
 -- | Apply the logic provided by 'defaultOnException' to determine if an
diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             3.1.1
+Version:             3.1.2
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             MIT
 License-file:        LICENSE