diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for http3
 
+## 0.0.23
+
+* Enclosing IPv6 address in :authority
+
 ## 0.0.22
 
 * Using `ThreadManager` of `time-manager`.
diff --git a/Network/HQ/Client.hs b/Network/HQ/Client.hs
--- a/Network/HQ/Client.hs
+++ b/Network/HQ/Client.hs
@@ -1,6 +1,5 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE RecordWildCards #-}
 
 -- | A client library for HTTP/0.9.
 module Network.HQ.Client (
diff --git a/Network/HQ/Server.hs b/Network/HQ/Server.hs
--- a/Network/HQ/Server.hs
+++ b/Network/HQ/Server.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE RecordWildCards #-}
 
 -- | A server library for HTTP/0.9.
 module Network.HQ.Server (
diff --git a/Network/HTTP3/Client.hs b/Network/HTTP3/Client.hs
--- a/Network/HTTP3/Client.hs
+++ b/Network/HTTP3/Client.hs
@@ -19,13 +19,15 @@
 
 import Control.Concurrent
 import qualified Control.Exception as E
-import qualified Data.ByteString.Char8 as C8
+import qualified Data.ByteString.UTF8 as UTF8
 import Data.IORef
+import Data.IP (IPv6)
 import Network.HTTP.Semantics.Client
 import Network.HTTP.Semantics.Client.Internal
 import Network.QUIC (Connection)
 import qualified Network.QUIC as QUIC
 import Network.QUIC.Internal (possibleMyStreams)
+import Text.Read (readMaybe)
 
 import Imports
 import Network.HTTP3.Config
@@ -96,4 +98,8 @@
                 processResponse rsp
   where
     hdr = outObjHeaders outobj
-    hdr' = (":scheme", scm) : (":authority", C8.pack auth) : hdr
+    isIPv6 = isJust (readMaybe auth :: Maybe IPv6)
+    auth'
+        | isIPv6 = "[" <> UTF8.fromString auth <> "]"
+        | otherwise = UTF8.fromString auth
+    hdr' = (":scheme", scm) : (":authority", auth') : hdr
diff --git a/Network/QPACK/Error.hs b/Network/QPACK/Error.hs
--- a/Network/QPACK/Error.hs
+++ b/Network/QPACK/Error.hs
@@ -13,7 +13,6 @@
 ) where
 
 import Control.Exception
-import Data.Typeable
 
 import Network.QUIC
 
@@ -31,12 +30,12 @@
 data DecodeError
     = IllegalStaticIndex
     | IllegalInsertCount
-    deriving (Eq, Show, Typeable)
+    deriving (Eq, Show)
 
 data EncoderInstructionError = EncoderInstructionError
-    deriving (Eq, Show, Typeable)
+    deriving (Eq, Show)
 data DecoderInstructionError = DecoderInstructionError
-    deriving (Eq, Show, Typeable)
+    deriving (Eq, Show)
 
 instance Exception DecodeError
 instance Exception EncoderInstructionError
diff --git a/Network/QPACK/Table/Dynamic.hs b/Network/QPACK/Table/Dynamic.hs
--- a/Network/QPACK/Table/Dynamic.hs
+++ b/Network/QPACK/Table/Dynamic.hs
@@ -183,9 +183,9 @@
         x <- readTVar insertionPoint
         writeTVar insertionPoint (x + 1)
         return x
-    maxN <- atomically $ readTVar maxNumOfEntries
+    maxN <- readTVarIO maxNumOfEntries
     let i = insp `mod` maxN
-    table <- atomically $ readTVar circularTable
+    table <- readTVarIO circularTable
     atomically $ unsafeWrite table i ent
     let revtbl = getRevIndex dyntbl
     let ai = AbsoluteIndex insp
diff --git a/Network/QPACK/Table/RevIndex.hs b/Network/QPACK/Table/RevIndex.hs
--- a/Network/QPACK/Table/RevIndex.hs
+++ b/Network/QPACK/Table/RevIndex.hs
@@ -77,7 +77,9 @@
         lst =
             zipWith (\(k, v) i -> (k, (v, i))) staticTableList $
                 map (SIndex . AbsoluteIndex) [0 ..]
-        extract xs = (fst (head xs), map snd xs)
+        extract xs = (headFst xs, map snd xs)
+        headFst [] = error "headFst"
+        headFst (x : _) = fst x
 
 {-# INLINE lookupStaticRevIndex #-}
 lookupStaticRevIndex :: Int -> FieldValue -> RevResult
diff --git a/http3.cabal b/http3.cabal
--- a/http3.cabal
+++ b/http3.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.4
 name:               http3
-version:            0.0.22
+version:            0.0.23
 license:            BSD-3-Clause
 license-file:       LICENSE
 maintainer:         Kazu Yamamoto <kazu@iij.ad.jp>
@@ -77,20 +77,22 @@
     ghc-options:        -Wall
     build-depends:
         base >=4.9 && <5,
-        async,
         array,
+        async,
         bytestring,
         case-insensitive,
         containers,
         http-semantics >= 0.3 && <0.4,
         http-types,
         http2 >=5.3.4 && <5.4,
+        iproute >= 1.7 && < 1.8,
         network,
         network-byte-order,
-        quic >= 0.2 && < 0.3,
+        quic >= 0.2.11 && < 0.3,
         sockaddr,
         stm,
-        time-manager >= 0.2 && < 0.3
+        time-manager >= 0.2 && < 0.3,
+        utf8-string >=1.0 && <1.1
 
 executable h3-server
     main-is:            h3-server.hs
diff --git a/test/HTTP3/ErrorSpec.hs b/test/HTTP3/ErrorSpec.hs
--- a/test/HTTP3/ErrorSpec.hs
+++ b/test/HTTP3/ErrorSpec.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE OverloadedStrings #-}
-
 module HTTP3.ErrorSpec where
 
 import Data.ByteString ()
diff --git a/test/HTTP3/Server.hs b/test/HTTP3/Server.hs
--- a/test/HTTP3/Server.hs
+++ b/test/HTTP3/Server.hs
@@ -93,4 +93,6 @@
     ctx' = CH.hashUpdate ctx bs
 
 firstTrailerValue :: TokenHeaderTable -> FieldValue
-firstTrailerValue = snd . Prelude.head . fst
+firstTrailerValue tbl = case fst tbl of
+    [] -> error "firstTrailerValue"
+    x : _ -> snd x
diff --git a/test/QPACK/QIFSpec.hs b/test/QPACK/QIFSpec.hs
--- a/test/QPACK/QIFSpec.hs
+++ b/test/QPACK/QIFSpec.hs
@@ -69,7 +69,7 @@
   where
     loop = do
         hdr' <- fromCaseSensitive <$> headerlist h
-        if hdr' == []
+        if null hdr'
             then
                 putMVar mvar ()
             else do
diff --git a/util/Common.hs b/util/Common.hs
--- a/util/Common.hs
+++ b/util/Common.hs
@@ -36,9 +36,9 @@
 split :: Char -> String -> [String]
 split _ "" = []
 split c s = case break (c ==) s of
-    ("", r) -> split c (tail r)
+    ("", r) -> split c (drop 1 r)
     (s', "") -> [s']
-    (s', r) -> s' : split c (tail r)
+    (s', r) -> s' : split c (drop 1 r)
 
 getLogger :: Maybe FilePath -> (String -> IO ())
 getLogger Nothing = \_ -> return ()