diff --git a/posix-socket.cabal b/posix-socket.cabal
--- a/posix-socket.cabal
+++ b/posix-socket.cabal
@@ -1,5 +1,5 @@
 Name: posix-socket
-Version: 0.1
+Version: 0.2
 Category: System
 Stability: experimental
 Synopsis: Bindings to the POSIX socket API
diff --git a/src/System/Posix/Socket.hsc b/src/System/Posix/Socket.hsc
--- a/src/System/Posix/Socket.hsc
+++ b/src/System/Posix/Socket.hsc
@@ -10,35 +10,38 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE PatternSynonyms #-}
 
 -- | POSIX sockets.
 module System.Posix.Socket
-  ( Socket
+  (
+  -- * Socket types
+    Socket
   , withSocketFd
   , unsafeSocketFd
   , unsafeSocketFromFd
   , SockFamily(..)
   , SockAddr(..)
   , SockType(..)
-  , streamSockType
-  , datagramSockType
-  , rawSockType
-  , seqPacketSockType
+  , pattern SOCK_STREAM
+  , pattern SOCK_DGRAM
+  , pattern SOCK_RAW
+  , pattern SOCK_RDM
+  , pattern SOCK_SEQPACKET
   , SockProto(..)
   , defaultSockProto
   , SockOpt(..)
   , SO_ERROR(..)
   , SO_KEEPALIVE(..)
   , SO_REUSEADDR(..)
-  , SockOps
-  , sendSockOp
-  , recvSockOp
-  , MsgFlags
-  , peekMsgFlag
-  , truncMsgFlag
-  , oobMsgFlag
-  , dontRouteMsgFlag
-
+  , SockOps(..)
+  , MsgFlags(..)
+  , pattern MSG_PEEK
+  , pattern MSG_TRUNC
+  , pattern MSG_OOB
+  , pattern MSG_DONTROUTE
+  -- * Socket operations
+  -- ** Creating and connecting
   , socket
   , getSockOpt
   , setSockOpt
@@ -47,8 +50,10 @@
   , tryConnect
   , listen
   , accept
+  , tryAccept
   , getLocalAddr
   , getRemoteAddr
+  -- ** Receiving messages
   , hasOobData
   , recvBufs
   , recvBuf
@@ -58,6 +63,7 @@
   , recvBufFrom
   , recvFrom'
   , recvFrom
+  -- ** Sending messages
   , sendBufs
   , sendMany'
   , sendMany
@@ -70,6 +76,7 @@
   , sendBufTo
   , sendTo'
   , sendTo
+  -- ** Closing
   , shutdown
   , close
   ) where
@@ -83,8 +90,7 @@
 import Data.ByteString (ByteString)
 import qualified Data.ByteString.Internal as BS
 import qualified Data.ByteString.Unsafe as BS
-import Data.Flags (Flags(..), (.>=.))
-import Data.Flags.TH (bitmaskWrapper)
+import Data.Flags (Flags(..), BoundedFlags(..), (.>=.))
 import Data.Foldable (forM_)
 import Control.Applicative ((<$>))
 import Control.Monad (void, when, foldM)
@@ -141,10 +147,12 @@
 -- | Get the underlying file descriptor.
 unsafeSocketFd ∷ MonadBase IO μ ⇒ Socket f → μ Fd
 unsafeSocketFd (Socket v) = liftBase $ readMVar v
+{-# INLINE unsafeSocketFd #-}
 
 -- | Use file descriptor as a socket.
 unsafeSocketFromFd ∷ MonadBase IO μ ⇒ Fd → μ (Socket f)
 unsafeSocketFromFd = liftBase . fmap Socket . newMVar
+{-# INLINE unsafeSocketFromFd #-}
 
 -- | Socket address.
 class SockAddr a where
@@ -170,22 +178,26 @@
 -- | Socket type.
 newtype SockType = SockType CInt deriving (Typeable, Eq, Ord, Show, Storable)
 
--- | See /SOCK_STREAM/.
-streamSockType ∷ SockType
-streamSockType = SockType #const SOCK_STREAM
+-- | See /socket(2)/.
+pattern SOCK_STREAM ∷ SockType
+pattern SOCK_STREAM = SockType #const SOCK_STREAM
 
--- | See /SOCK_DGRAM/.
-datagramSockType ∷ SockType
-datagramSockType = SockType #const SOCK_DGRAM
+-- | See /socket(2)/.
+pattern SOCK_DGRAM ∷ SockType
+pattern SOCK_DGRAM = SockType #const SOCK_DGRAM
 
--- | See /SOCK_RAW/.
-rawSockType ∷ SockType
-rawSockType = SockType #const SOCK_RAW
+-- | See /socket(2)/.
+pattern SOCK_RAW ∷ SockType
+pattern SOCK_RAW = SockType #const SOCK_RAW
 
--- | See /SOCK_SEQPACKET/.
-seqPacketSockType ∷ SockType
-seqPacketSockType = SockType #const SOCK_SEQPACKET
+-- | See /socket(2)/.
+pattern SOCK_RDM ∷ SockType
+pattern SOCK_RDM = SockType #const SOCK_RDM
 
+-- | See /socket(2)/.
+pattern SOCK_SEQPACKET ∷ SockType
+pattern SOCK_SEQPACKET = SockType #const SOCK_SEQPACKET
+
 -- | Socket protocol.
 newtype SockProto = SockProto CInt deriving (Typeable, Eq, Ord, Show, Storable)
 
@@ -253,29 +265,49 @@
   sockOptLevel _ = #const SOL_SOCKET
   sockOptCode  _ = #const SO_REUSEADDR
 
--- | Socket operations. Used by 'shutdown'.
-$(bitmaskWrapper "SockOps" ''Int []
-    [("sendSockOp", 1),
-     ("recvSockOp", 2)])
+-- | Socket operations.
+data SockOps = NoSockOps
+             | RecvSockOps
+             | SendSockOps
+             | AllSockOps
+             deriving (Typeable, Show, Read, Eq)
 
+instance Flags SockOps where
+  noFlags = NoSockOps
+  andFlags NoSockOps ops = ops
+  andFlags ops NoSockOps = ops
+  andFlags ops1 ops2 | ops1 == ops2 = ops1
+  andFlags _ _ = AllSockOps
+  butFlags _ AllSockOps = NoSockOps
+  butFlags ops1 ops2 | ops1 == ops2 = NoSockOps
+  butFlags ops _ = ops
+  commonFlags AllSockOps ops = ops
+  commonFlags ops AllSockOps = ops
+  commonFlags ops1 ops2 | ops1 == ops2 = ops1
+  commonFlags _ _ = NoSockOps
+
+instance BoundedFlags SockOps where
+  allFlags = AllSockOps
+  enumFlags f = filter (f .>=.) [RecvSockOps, SendSockOps]
+
 -- | Message flags.
 newtype MsgFlags = MsgFlags CInt deriving (Typeable, Eq, Show, Storable, Flags)
 
--- | See /MSG_PEEK/.
-peekMsgFlag ∷ MsgFlags
-peekMsgFlag = MsgFlags #const MSG_PEEK
+-- | See /recvmsg(2)/ and /sendmsg(2)/.
+pattern MSG_PEEK ∷ MsgFlags
+pattern MSG_PEEK = MsgFlags #const MSG_PEEK
 
--- | See /MSG_TRUNC/.
-truncMsgFlag ∷ MsgFlags
-truncMsgFlag = MsgFlags #const MSG_TRUNC
+-- | See /recvmsg(2)/ and /sendmsg(2)/.
+pattern MSG_TRUNC ∷ MsgFlags
+pattern MSG_TRUNC = MsgFlags #const MSG_TRUNC
 
--- | See /MSG_OOB/.
-oobMsgFlag ∷ MsgFlags
-oobMsgFlag = MsgFlags #const MSG_OOB
+-- | See /recvmsg(2)/ and /sendmsg(2)/.
+pattern MSG_OOB ∷ MsgFlags
+pattern MSG_OOB = MsgFlags #const MSG_OOB
 
--- | See /MSG_DONTROUTE/.
-dontRouteMsgFlag ∷ MsgFlags
-dontRouteMsgFlag = MsgFlags #const MSG_DONTROUTE
+-- | See /recvmsg(2)/ and /sendmsg(2)/.
+pattern MSG_DONTROUTE ∷ MsgFlags
+pattern MSG_DONTROUTE = MsgFlags #const MSG_DONTROUTE
 
 allocaMaxAddr ∷ SockAddr a ⇒ Proxy a → (Ptr a → #{itype socklen_t} → IO α) → IO α
 allocaMaxAddr addrProxy f =
@@ -312,8 +344,8 @@
   where famCode ∷ #{itype sa_family_t}
         famCode = fromIntegral $ sockFamilyCode fam
 
--- | Create a socket. See /socket(3)/.
--- The underlying file descriptor is non-blocking.
+-- | Create a socket. The underlying file descriptor is non-blocking. All
+-- blocking operations are done via the GHC event manager. See /socket(2)/.
 socket ∷ (SockFamily f, MonadBase IO μ)
        ⇒ f → SockType → SockProto → μ (Socket f)
 socket f (SockType t) p = liftBase $ do
@@ -336,12 +368,12 @@
         c_getsockopt fd (sockOptLevel o) (sockOptCode o) p pSize
       sockOptValue o <$> peek p
 
--- | Get socket option value. See /getsockopt(3)/.
+-- | Get socket option value. See /getsockopt(2)/.
 getSockOpt ∷ (SockOpt o, SockOptReadable o ~ 'True, MonadBase IO μ)
            ⇒ Socket f → o → μ (SockOptValue o)
 getSockOpt s o = withSocketFd s $ \fd → getFdOpt fd o
 
--- | Set socket option value. See /setsockopt(3)/.
+-- | Set socket option value. See /setsockopt(2)/.
 setSockOpt ∷ (SockOpt o, SockOptWritable o ~ 'True, MonadBase IO μ)
            ⇒ Socket f → o → SockOptValue o → μ ()
 setSockOpt s o v = withSocketFd s $ \fd →
@@ -351,15 +383,15 @@
           fromIntegral (sizeOf raw)
   where raw = sockOptRaw o v
 
--- | Bind socket to the specified address. See /bind(3)/.
+-- | Bind socket to the specified address. See /bind(2)/.
 bind ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
      ⇒ Socket f → SockFamilyAddr f → μ ()
 bind s addr = withSocketFd s $ \fd →
   withAddr (undefined ∷ f) addr $ \p size →
     throwErrnoIfMinus1_ "bind" $ c_bind fd p $ fromIntegral size
 
--- | Connect socket to the specified address. This function blocks.
--- See /connect(3)/.
+-- | Connect socket to the specified address. This operation blocks.
+-- See /connect(2)/.
 connect ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
         ⇒ Socket f → SockFamilyAddr f → μ ()
 connect s addr = withSocketFd s $ \fd →
@@ -381,7 +413,7 @@
 
 -- | Try to connect socket without blocking. On success 'True' is returned.
 -- If the connection did not succeed immediately, 'False' is returned.
--- See /connect(3)/.
+-- See /connect(2)/.
 tryConnect ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
            ⇒ Socket f → SockFamilyAddr f → μ Bool
 tryConnect s addr = withSocketFd s $ \fd →
@@ -401,7 +433,7 @@
 listen s backlog = withSocketFd s $ \fd →
   throwErrnoIfMinus1_ "listen" $ c_listen fd $ fromIntegral backlog
 
--- | Accept a connection on the given socket. This function blocks.
+-- | Accept a connection on the given socket. This operation blocks.
 -- See /accept(2)/.
 accept ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
        ⇒ Socket f → μ (Socket f, SockFamilyAddr f)
@@ -422,12 +454,38 @@
               _ → throwErrno "accept"
           else do
             addr ← peekAddrOfSize (undefined ∷ f) p pSize
+            let accFd = Fd cfd
 #ifndef HAVE_ACCEPT_WITH_FLAGS
-            setNonBlockingFD cfd True
+            onException (setNonBlockingFD accFd True) (closeFd accFd)
 #endif
-            (, addr) <$> unsafeSocketFromFd (Fd cfd)
+            (, addr) <$> unsafeSocketFromFd accFd
 
--- | Get the local address. See /getsockname(3)/.
+-- | Try to accept a connection on the given socket without blocking.
+-- On success the accepted socket and the peer address are returned.
+-- See /accept(2)/.
+tryAccept ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
+          ⇒ Socket f → μ (Maybe (Socket f, SockFamilyAddr f))
+tryAccept s = withSocketFd s $ \fd →
+    allocaMaxAddr (Proxy ∷ Proxy (SockFamilyAddr f)) $ \p size →
+      with size $ \pSize → do
+        cfd ← c_accept fd p pSize
+#ifdef HAVE_ACCEPT_WITH_FLAGS
+                #{const SOCK_NONBLOCK}
+#endif
+        if cfd == -1 then do
+          errno ← getErrno
+          case errno of
+            e | e == eAGAIN || e == eWOULDBLOCK → return Nothing
+            _ → throwErrno "accept"
+        else do
+          addr ← peekAddrOfSize (undefined ∷ f) p pSize
+          let accFd = Fd cfd
+#ifndef HAVE_ACCEPT_WITH_FLAGS
+          onException (setNonBlockingFD accFd True) (closeFd accFd)
+#endif
+          Just . (, addr) <$> unsafeSocketFromFd accFd
+
+-- | Get the local address. See /getsockname(2)/.
 getLocalAddr ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
              ⇒ Socket f → μ (SockFamilyAddr f)
 getLocalAddr s = withSocketFd s $ \fd →
@@ -436,7 +494,7 @@
       throwErrnoIfMinus1_ "getLocalAddr" $ c_getsockname fd p pSize
       peekAddrOfSize (undefined ∷ f) p pSize
 
--- | Get the remote address. See /getpeername(3)/.
+-- | Get the remote address. See /getpeername(2)/.
 getRemoteAddr ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
               ⇒ Socket f → μ (SockFamilyAddr f)
 getRemoteAddr s = withSocketFd s $ \fd →
@@ -510,7 +568,7 @@
   recvBufsFromFd (undefined ∷ f) fd bufs flags
 
 -- | Receive a message from a connected socket, possibly utilizing multiple
--- memory buffers. See /recvmsg(3)/.
+-- memory buffers. See /recvmsg(2)/.
 recvBufs ∷ (SockFamily f, MonadBase IO μ)
          ⇒ Socket f           -- ^ The socket
          → [(Ptr Word8, Int)] -- ^ Memory buffers
@@ -520,7 +578,8 @@
   (_, r, flags') ← recvBufsFrom' s bufs flags
   return (r, flags')
 
--- | Receive a message from a connected socket. See /recvmsg(3)/.
+-- | Receive a message from a connected socket. This operation blocks.
+-- See /recvmsg(2)/.
 recvBuf ∷ (SockFamily f, MonadBase IO μ)
         ⇒ Socket f          -- ^ The socket
         → Ptr α             -- ^ Buffer pointer
@@ -529,7 +588,8 @@
         → μ (Int, MsgFlags) -- ^ Received message length and flags
 recvBuf s p len flags = recvBufs s [(castPtr p, len)] flags
 
--- | Receive a message from a connected socket. See /recvmsg(3)/.
+-- | Receive a message from a connected socket. This operation blocks.
+-- See /recvmsg(2)/.
 recv' ∷ (SockFamily f, MonadBase IO μ)
       ⇒ Socket f                 -- ^ The socket
       → Int                      -- ^ Maximum message length
@@ -540,7 +600,8 @@
     (r, flags') ← recvBuf s p len flags
     return (0, r, flags')
 
--- | Receive a message from a connected socket. See /recvmsg(3)/.
+-- | Receive a message from a connected socket. This operation blocks.
+-- See /recvmsg(2)/.
 recv ∷ (SockFamily f, MonadBase IO μ)
      ⇒ Socket f     -- ^ The socket
      → Int          -- ^ Maximum message length
@@ -548,7 +609,7 @@
 recv s len = fst <$> recv' s len noFlags
 
 -- | Receive a message from an unconnected socket, possibly utilizing multiple
--- memory buffers. See /recvmsg(3)/.
+-- memory buffers. This operation blocks. See /recvmsg(2)/.
 recvBufsFrom ∷ ∀ f μ . (SockFamily f, MonadBase IO μ)
              ⇒ Socket f                            -- ^ The socket
              → [(Ptr Word8, Int)]                  -- ^ Memory buffers
@@ -564,7 +625,8 @@
             peekAddrOfSize (undefined ∷ f) p pSize
   (, n, flags') <$> maybe getpeername return mAddr
 
--- | Receive a message from an unconnected socket. See /recvmsg(3)/.
+-- | Receive a message from an unconnected socket. This operation blocks.
+-- See /recvmsg(2)/.
 recvBufFrom ∷ (SockFamily f, MonadBase IO μ)
             ⇒ Socket f -- ^ The socket
             → Ptr α    -- ^ Buffer pointer
@@ -574,7 +636,8 @@
             -- ^ Received message source address, length, and flags
 recvBufFrom s p len flags = recvBufsFrom s [(castPtr p, len)] flags
 
--- | Receive a message from an unconnected socket. See /recvmsg(3)/.
+-- | Receive a message from an unconnected socket. This operation blocks.
+-- See /recvmsg(2)/.
 recvFrom' ∷ (SockFamily f, MonadBase IO μ)
           ⇒ Socket f -- ^ The socket
           → Int      -- ^ Maximum message length
@@ -587,7 +650,8 @@
     return (0, len', (addr, flags'))
   return (addr, bs, flags')
 
--- | Receive a message from an unconnected socket. See /recvmsg(3)/.
+-- | Receive a message from an unconnected socket. This operation blocks.
+-- See /recvmsg(2)/.
 recvFrom ∷ (SockFamily f, MonadBase IO μ)
          ⇒ Socket f -- ^ The socket
          → Int      -- ^ Maximum message length
@@ -643,12 +707,12 @@
         cont
 
 -- | Send a message split into several memory buffers on a connected socket.
--- See /sendmsg(3)/.
+-- This operation blocks. See /sendmsg(2)/.
 sendBufs ∷ (SockFamily f, MonadBase IO μ)
          ⇒ Socket f           -- ^ The socket
          → [(Ptr Word8, Int)] -- ^ Memory buffers
          → MsgFlags           -- ^ Message flags
-         → μ Int              -- ^ The number of bytes sent 
+         → μ Int              -- ^ The number of bytes sent
 sendBufs s bufs flags = _sendBufs s bufs flags Nothing
 
 withBufs ∷ [ByteString] → ([(Ptr Word8, Int)] → IO α) → IO α
@@ -658,7 +722,7 @@
                                  go bss' ((castPtr p, len) : rbufs)
 
 -- | Send a message split into several 'ByteString's on a connected socket.
--- See /sendmsg(3)/.
+-- This operation blocks. See /sendmsg(2)/.
 sendMany' ∷ (SockFamily f, MonadBase IO μ)
           ⇒ Socket f     -- ^ The socket
           → [ByteString] -- ^ Message contents
@@ -668,14 +732,15 @@
   liftBase $ withBufs bss $ \bufs → sendBufs s bufs flags
 
 -- | Send a message split into several 'ByteString's on a connected socket.
--- See /sendmsg(3)/.
+-- This operation blocks. See /sendmsg(2)/.
 sendMany ∷ (SockFamily f, MonadBase IO μ)
          ⇒ Socket f     -- ^ The socket
          → [ByteString] -- ^ Message contents
          → μ Int        -- ^ The number of bytes sent
 sendMany s bss = sendMany' s bss noFlags
 
--- | Send a message on a connected socket. See /sendmsg(3)/.
+-- | Send a message on a connected socket. This operation blocks.
+-- See /sendmsg(2)/.
 sendBuf ∷ (SockFamily f, MonadBase IO μ)
         ⇒ Socket f -- ^ The socket
         → Ptr α    -- ^ Buffer pointer
@@ -684,7 +749,8 @@
         → μ Int    -- ^ The number of bytes sent
 sendBuf s p len flags = sendBufs s [(castPtr p, len)] flags
 
--- | Send a message on a connected socket. See /sendmsg(3)/.
+-- | Send a message on a connected socket. This operation blocks.
+-- See /sendmsg(2)/.
 send' ∷ (SockFamily f, MonadBase IO μ)
       ⇒ Socket f   -- ^ The socket
       → ByteString -- ^ Message contents
@@ -693,7 +759,8 @@
 send' s bs flags = liftBase $ BS.unsafeUseAsCStringLen bs $ \(p, len) →
                      sendBuf s p len flags
 
--- | Send a message on a connected socket. See /sendmsg(3)/.
+-- | Send a message on a connected socket. This operation blocks.
+-- See /sendmsg(2)/.
 send ∷ (SockFamily f, MonadBase IO μ)
      ⇒ Socket f   -- ^ The socket
      → ByteString -- ^ Message contents
@@ -701,7 +768,7 @@
 send s bs = send' s bs noFlags
 
 -- | Send a message split into several memory buffers on an unconnected
--- socket. See /sendmsg(3)/.
+-- socket. This operation blocks. See /sendmsg(2)/.
 sendBufsTo ∷ (SockFamily f, MonadBase IO μ)
            ⇒ Socket f           -- ^ The socket
            → [(Ptr Word8, Int)] -- ^ Memory buffers
@@ -711,7 +778,7 @@
 sendBufsTo s bufs flags addr = _sendBufs s bufs flags (Just addr)
 
 -- | Send a message split into several 'ByteString's on an unconnected socket.
--- See /sendmsg(3)/.
+-- This operation blocks. See /sendmsg(2)/.
 sendManyTo' ∷ (SockFamily f, MonadBase IO μ)
             ⇒ Socket f         -- ^ The socket
             → [ByteString]     -- ^ Message contents
@@ -722,7 +789,7 @@
                                  sendBufsTo s bufs flags addr
 
 -- | Send a message split into several 'ByteString's on an unconnected socket.
--- See /sendmsg(3)/.
+-- This operation blocks. See /sendmsg(2)/.
 sendManyTo ∷ (SockFamily f, MonadBase IO μ)
            ⇒ Socket f         -- ^ The socket
            → [ByteString]     -- ^ Message contents
@@ -730,7 +797,8 @@
            → μ Int            -- ^ The number of bytes sent
 sendManyTo s bss addr = sendManyTo' s bss noFlags addr
 
--- | Send a message on an unconnected socket. See /sendmsg(3)/.
+-- | Send a message on an unconnected socket. This operation blocks.
+-- See /sendmsg(2)/.
 sendBufTo ∷ (SockFamily f, MonadBase IO μ)
           ⇒ Socket f         -- ^ The socket
           → Ptr α            -- ^ Buffer pointer
@@ -740,7 +808,8 @@
           → μ Int            -- ^ The number of bytes sent
 sendBufTo s p len flags addr = sendBufsTo s [(castPtr p, len)] flags addr
 
--- | Send a message on an unconnected socket. See /sendmsg(3)/.
+-- | Send a message on an unconnected socket. This operation blocks.
+-- See /sendmsg(2)/.
 sendTo' ∷ (SockFamily f, MonadBase IO μ)
         ⇒ Socket f         -- ^ The socket
         → ByteString       -- ^ Message contents
@@ -751,7 +820,8 @@
   liftBase $ BS.unsafeUseAsCStringLen bs $ \(p, len) →
     sendBufTo s p len flags addr
 
--- | Send a message on an unconnected socket. See /sendmsg(3)/.
+-- | Send a message on an unconnected socket. This operation blocks.
+-- See /sendmsg(2)/.
 sendTo ∷ (SockFamily f, MonadBase IO μ)
        ⇒ Socket f         -- ^ The socket
        → ByteString       -- ^ Message contents
@@ -759,22 +829,22 @@
        → μ Int            -- ^ The number of bytes sent
 sendTo s bs addr = sendTo' s bs noFlags addr
 
--- | Shut down a part of a full-duplex connection. See /shutdown(3)/.
+-- | Shut down a part of a full-duplex connection. See /shutdown(2)/.
 shutdown ∷ MonadBase IO μ ⇒ Socket f → SockOps → μ ()
 shutdown s dirs = withSocketFd s $ \fd →
     forM_ how $ throwErrnoIfMinus1_ "shutdown" . c_shutdown fd
-  where how = if dirs .>=. sendSockOp then
-                if dirs .>=. recvSockOp then
+  where how = if dirs .>=. SendSockOps then
+                if dirs .>=. RecvSockOps then
                   Just #{const SHUT_RDWR}
                 else
                   Just #{const SHUT_WR}
               else
-                if dirs .>=. recvSockOp then
+                if dirs .>=. RecvSockOps then
                   Just #{const SHUT_RD}
                 else
                   Nothing
 
--- | Close the socket. See /close(3)/.
+-- | Close the socket. See /close(2)/.
 close ∷ MonadBase IO μ ⇒ Socket f → μ ()
 close (Socket v) = liftBase $ modifyMVar_ v $ \fd → do
   when (fd >= 0) $ closeFdWith closeFd fd