diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+0.6.4
+-----------------------------------------------------------------------------
+- Update dependencies.
+
 0.6.3
 -----------------------------------------------------------------------------
 - Make internal modules available.
diff --git a/src/System/ZMQ4.hs b/src/System/ZMQ4.hs
--- a/src/System/ZMQ4.hs
+++ b/src/System/ZMQ4.hs
@@ -206,7 +206,6 @@
   , curveKeyPair
   ) where
 
-import Prelude hiding (init)
 import Control.Applicative
 import Control.Exception
 import Control.Monad (unless)
@@ -223,6 +222,7 @@
 import System.ZMQ4.Internal
 import System.ZMQ4.Internal.Base
 import System.ZMQ4.Internal.Error
+import Prelude hiding (init)
 
 import qualified Data.ByteString           as SB
 import qualified Data.ByteString.Lazy      as LB
diff --git a/src/System/ZMQ4/Internal.hs b/src/System/ZMQ4/Internal.hs
--- a/src/System/ZMQ4/Internal.hs
+++ b/src/System/ZMQ4/Internal.hs
@@ -72,6 +72,7 @@
 import Data.IORef (newIORef)
 import Data.Restricted
 import Data.Typeable
+import Prelude
 
 import System.Posix.Types (Fd(..))
 import System.ZMQ4.Internal.Base
diff --git a/src/System/ZMQ4/Internal/Base.hsc b/src/System/ZMQ4/Internal/Base.hsc
--- a/src/System/ZMQ4/Internal/Base.hsc
+++ b/src/System/ZMQ4/Internal/Base.hsc
@@ -10,6 +10,7 @@
 import Foreign.C.Types
 import Foreign.C.String
 import Control.Applicative
+import Prelude
 
 #include <zmq.h>
 
diff --git a/src/System/ZMQ4/Internal/Error.hs b/src/System/ZMQ4/Internal/Error.hs
--- a/src/System/ZMQ4/Internal/Error.hs
+++ b/src/System/ZMQ4/Internal/Error.hs
@@ -20,6 +20,7 @@
 import Foreign.C.Error
 import Foreign.C.String
 import Foreign.C.Types (CInt)
+import Prelude
 
 import System.ZMQ4.Internal.Base
 
diff --git a/src/System/ZMQ4/Monadic.hs b/src/System/ZMQ4/Monadic.hs
--- a/src/System/ZMQ4/Monadic.hs
+++ b/src/System/ZMQ4/Monadic.hs
@@ -193,6 +193,7 @@
 import Data.Word
 import Data.ByteString (ByteString)
 import System.Posix.Types (Fd)
+import Prelude
 
 import qualified Control.Concurrent.Async as A
 import qualified Control.Exception        as E
diff --git a/tests/System/ZMQ4/Test/Properties.hs b/tests/System/ZMQ4/Test/Properties.hs
--- a/tests/System/ZMQ4/Test/Properties.hs
+++ b/tests/System/ZMQ4/Test/Properties.hs
@@ -20,6 +20,7 @@
 import Data.ByteString (ByteString)
 import System.ZMQ4.Monadic
 import System.Posix.Types (Fd(..))
+import Prelude
 
 import qualified Data.ByteString         as SB
 import qualified Data.ByteString.Char8   as CB
diff --git a/zeromq4-haskell.cabal b/zeromq4-haskell.cabal
--- a/zeromq4-haskell.cabal
+++ b/zeromq4-haskell.cabal
@@ -1,5 +1,5 @@
 name:               zeromq4-haskell
-version:            0.6.3
+version:            0.6.4
 synopsis:           Bindings to ZeroMQ 4.x
 category:           System, FFI
 license:            MIT
@@ -52,7 +52,7 @@
 
     build-depends:
           base         >= 3 && < 5
-        , async        == 2.0.*
+        , async        >= 2.0 && < 3.0
         , bytestring
         , containers
         , exceptions   >= 0.6 && < 1.0