diff --git a/Changelog.md b/Changelog.md
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,10 @@
 # Revision history for network-control
 
+## 0.1.1
+
+* Change defaultMaxData
+  [#4](https://github.com/kazu-yamamoto/network-control/pull/4)
+
 ## 0.1.0
 
 * Breaking change: Renaming rxfWindow to rxfBufSize.
diff --git a/Network/Control/Flow.hs b/Network/Control/Flow.hs
--- a/Network/Control/Flow.hs
+++ b/Network/Control/Flow.hs
@@ -21,6 +21,7 @@
     -- ** Flow control for receiving
     RxFlow (..),
     newRxFlow,
+    rxWindowSize,
     FlowControlType (..),
     maybeOpenRxWindow,
     checkRxLimit,
@@ -36,9 +37,18 @@
 defaultMaxStreamData :: Int
 defaultMaxStreamData = 262144
 
--- | Default max data of a connection. (1M bytes)
+-- | Default max data of a connection.
+--
+-- By default, this is set to @defaultMaxStreams * defaultMaxStreamData@. This
+-- ensures that streams that are not currently handled cannot exhaust the
+-- connection window.
+--
+-- If you use a smaller connection window size, you __must__ ensure that if you
+-- are handling fewer concurrent streams than allowed by 'defaultMaxStreams',
+-- that the unhandled streams cannot exhaust the connection window, or risk the
+-- entire system deadlocking.
 defaultMaxData :: Int
-defaultMaxData = 1048576
+defaultMaxData = defaultMaxStreamData * defaultMaxStreams
 
 -- | Window size.
 type WindowSize = Int
@@ -79,7 +89,7 @@
 --   rxfConsumed   rxfReceived  rxfLimit
 --
 --                     |-----------| The size which the peer can send
---                        Window
+--                      rxWindowSize
 -- @
 data RxFlow = RxFlow
     { rxfBufSize :: Int
@@ -96,6 +106,10 @@
 -- | Creating RX flow with an initial window size.
 newRxFlow :: WindowSize -> RxFlow
 newRxFlow win = RxFlow win 0 0 win
+
+-- | 'rxfLimit' - 'rxfReceived'.
+rxWindowSize :: RxFlow -> WindowSize
+rxWindowSize RxFlow{..} = rxfLimit - rxfReceived
 
 -- | The representation of window size update.
 data FlowControlType
diff --git a/network-control.cabal b/network-control.cabal
--- a/network-control.cabal
+++ b/network-control.cabal
@@ -1,6 +1,6 @@
 cabal-version:   3.0
 name:            network-control
-version:         0.1.0
+version:         0.1.1
 license:         BSD-3-Clause
 license-file:    LICENSE
 maintainer:      kazu@iij.ad.jp