diff --git a/.gitignore b/.gitignore
index 425e2d8..d9a126d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,4 @@ cabal-dev/
 network-bitcoin-tests
 cabal.sandbox.config
 .cabal-sandbox/
+tags
diff --git a/.hgignore b/.hgignore
index c499dd6..ab86da2 100644
--- a/.hgignore
+++ b/.hgignore
@@ -16,3 +16,4 @@ dist-newstyle/
 \.tfstate\.blank$
 \.terraform/
 \.stack-work/
+^tags$
diff --git a/src/Network/Bitcoin/BlockChain.hs b/src/Network/Bitcoin/BlockChain.hs
index 7fa94de..709f651 100644
--- a/src/Network/Bitcoin/BlockChain.hs
+++ b/src/Network/Bitcoin/BlockChain.hs
@@ -152,7 +152,7 @@ data OutputInfo =
                -- | The public key of the sender.
                , oiScriptPubKey  :: ScriptPubKey
                -- | The version of this transaction.
-               , oiVersion       :: Integer
+               , oiVersion       :: Maybe Integer
                -- | Is this transaction part of the coin base?
                , oiCoinBase      :: Bool
                }
@@ -163,7 +163,7 @@ instance FromJSON OutputInfo where
                                       <*> o .: "confirmations"
                                       <*> o .: "value"
                                       <*> o .: "scriptPubKey"
-                                      <*> o .: "version"
+                                      <*> o .:? "version"
                                       <*> o .: "coinbase"
     parseJSON _ = mzero
 
diff --git a/src/Network/Bitcoin/RawTransaction.hs b/src/Network/Bitcoin/RawTransaction.hs
index 00f38fc..0883759 100644
--- a/src/Network/Bitcoin/RawTransaction.hs
+++ b/src/Network/Bitcoin/RawTransaction.hs
@@ -241,9 +241,9 @@ instance FromJSON UnspentTransaction where
 
 -- Instance used in 'createRawTransaction'.
 instance ToJSON UnspentTransaction where
-    toJSON (UnspentTransaction{..}) = object [ "txid" .= unspentTransactionId
-                                             , "vout" .= outIdx
-                                             ]
+    toJSON UnspentTransaction{..} = object [ "txid" .= unspentTransactionId
+                                           , "vout" .= outIdx
+                                           ]
 
 -- | Returns an array of unspent transaction outputs with between minconf and
 --   maxconf (inclusive) confirmations. If addresses are given, the result will
@@ -306,7 +306,7 @@ decodeRawTransaction client tx = callApi client "decoderawtransaction" [ tj tx ]
 newtype UnspentForSigning = UFS UnspentTransaction
 
 instance ToJSON UnspentForSigning where
-    toJSON (UFS (UnspentTransaction{..}))
+    toJSON (UFS UnspentTransaction{..})
         | isNothing redeemScript =
             object [ "txid" .= unspentTransactionId
                    , "vout" .= outIdx
diff --git a/src/Network/Bitcoin/Wallet.hs b/src/Network/Bitcoin/Wallet.hs
index 02908b6..f68f3db 100644
--- a/src/Network/Bitcoin/Wallet.hs
+++ b/src/Network/Bitcoin/Wallet.hs
@@ -65,7 +65,6 @@ module Network.Bitcoin.Wallet ( Client
                               , isAddressValid
                               ) where
 
-import           Control.Applicative            (liftA2)
 import           Control.Monad
 import           Data.Aeson                     as A
 import           Data.Aeson.Types               (parseEither)
@@ -78,7 +77,7 @@ import           Data.Text
 import           Data.Time.Clock.POSIX
 import           Data.Vector                    as V hiding ((++))
 import           Data.Word
-import           Network.Bitcoin.BlockChain     (BlockHash, BlockHeight)
+import           Network.Bitcoin.BlockChain     (BlockHash)
 import           Network.Bitcoin.Internal
 import           Network.Bitcoin.RawTransaction (RawTransaction)
 
@@ -770,7 +769,7 @@ instance ToJSON EstimationMode where
 
 
 -- | Estimate the fee per kb to send a transaction
-estimateSmartFee :: Client -> Word32 -> Maybe EstimationMode -> IO (Either [String] (Double, BlockHeight))
+estimateSmartFee :: Client -> Word32 -> Maybe EstimationMode -> IO (Either [String] Double)
 estimateSmartFee client target mode =
     parse <$> callApi client "estimatesmartfee" (catMaybes [ Just $ tj target, tj <$> mode ])
     where
@@ -779,4 +778,4 @@ estimateSmartFee client target mode =
         merrs <- obj .:? "errors"
         flip (maybe (parseVals obj)) merrs $ \errs ->
             bool (pure $ Left errs) (parseVals obj) . List.null $ errs
-    parseVals = fmap Right . (liftA2 (,) <$> (.: "feerate") <*> (.: "blocks"))
+    parseVals = fmap Right . (.: "feerate")