diff --git a/src/Network/Ethereum/Web3/Contract.hs b/src/Network/Ethereum/Web3/Contract.hs
--- a/src/Network/Ethereum/Web3/Contract.hs
+++ b/src/Network/Ethereum/Web3/Contract.hs
@@ -11,7 +11,9 @@
 -- catch all event depend by given callback function type.
 --
 -- @
--- runWeb3 $ event "0x..." (\(MyEvent a b c) -> print (a + b * c))
+-- runWeb3 $ do
+--     event "0x..." $ \(MyEvent a b c) ->
+--         liftIO $ print (a + b * c))
 -- @
 --
 -- In other case 'call' function used for constant calls (without
@@ -21,7 +23,7 @@
 --
 -- @
 -- runweb3 $ do
---   x <- call "0x.." Latest MySelector
+--   x  <- call "0x.." Latest MySelector
 --   tx <- sendTx "0x.." nopay $ MySelector2 (x + 2)
 -- @
 --
@@ -127,8 +129,9 @@
 _sendTransaction to value dat = do
     primeAddress <- listToMaybe <$> eth_accounts
     eth_sendTransaction (txdata primeAddress $ Just $ toData dat)
-  where txdata from = Call from to Nothing Nothing (Just $ toWeiText value)
-        toWeiText = ("0x" <>) . toStrict . B.toLazyText . B.hexadecimal . toWei
+  where txdata from = Call from to (Just defaultGas) Nothing (Just $ toWeiText value)
+        toWeiText   = ("0x" <>) . toStrict . B.toLazyText . B.hexadecimal . toWei
+        defaultGas  = "0x2DC2DC"
 
 _call :: (Provider p, Method a, ABIEncoding b)
       => Address -> CallMode -> a -> Web3 p b
diff --git a/web3.cabal b/web3.cabal
--- a/web3.cabal
+++ b/web3.cabal
@@ -1,5 +1,5 @@
 name: web3
-version: 0.5.3.0
+version: 0.5.4.0
 cabal-version: >=1.10
 build-type: Simple
 license: BSD3
@@ -37,16 +37,16 @@
     build-depends:
         base >4.8 && <4.11,
         base16-bytestring >=0.1.1.6 && <0.2,
-        template-haskell >=2.11.0.0 && <2.12,
-        http-client-tls >=0.2.4.1 && <0.3,
+        template-haskell >=2.11.1.0 && <2.12,
+        http-client-tls >=0.3.3.1 && <0.4,
         transformers >=0.5.2.0 && <0.6,
-        http-client >=0.4.31.2 && <0.5,
+        http-client >=0.5.5 && <0.6,
         attoparsec >=0.13.1.0 && <0.14,
         bytestring >=0.10.8.1 && <0.11,
         cryptonite ==0.21.*,
         vector >=0.11.0.0 && <0.12,
-        memory ==0.13.*,
-        aeson >=0.11.2.1 && <0.12,
+        memory >=0.14.1 && <0.15,
+        aeson >=1.0.2.1 && <1.1,
         text >=1.2.2.1 && <1.3
     default-language: Haskell2010
     default-extensions: OverloadedStrings
@@ -61,10 +61,10 @@
     type: exitcode-stdio-1.0
     main-is: Spec.hs
     build-depends:
-        base >=4.9.0.0 && <4.10,
-        memory ==0.13.*,
+        base >=4.9.1.0 && <4.10,
+        memory >=0.14.1 && <0.15,
         text >=1.2.2.1 && <1.3,
-        web3 >=0.5.3.0 && <0.6
+        web3 >=0.5.4.0 && <0.6
     default-language: Haskell2010
     default-extensions: OverloadedStrings
     hs-source-dirs: test