diff --git a/network-bitcoin.cabal b/network-bitcoin.cabal
--- a/network-bitcoin.cabal
+++ b/network-bitcoin.cabal
@@ -1,5 +1,5 @@
 Name:                network-bitcoin
-Version:             1.2.0
+Version:             1.2.1
 Synopsis:            An interface to bitcoind.
 Description:
     This can be used to send Bitcoins, query balances, etc.  It
diff --git a/src/Network/Bitcoin/Internal.hs b/src/Network/Bitcoin/Internal.hs
--- a/src/Network/Bitcoin/Internal.hs
+++ b/src/Network/Bitcoin/Internal.hs
@@ -16,6 +16,7 @@
                                 , FromJSON(..)
                                 , callApi
                                 , callApi'
+                                , Nil(..)
                                 , tj
                                 , AddrAddress(..)
                                 ) where
@@ -108,6 +109,13 @@
                             , "id"      .= (1 :: Int)
                             ]
 {-# INLINE callApi #-}
+
+-- | Used to allow "null" to decode to a tuple.
+data Nil = Nil { unNil :: () }
+
+instance FromJSON Nil where
+    parseJSON Null = return $ Nil ()
+    parseJSON x    = fail $ "\"null\" was expected, but " ++ show x ++ " was recieved."
 
 -- | Internal helper functions to make callApi more readable
 httpAuthority :: Auth -> Authority
diff --git a/src/Network/Bitcoin/Mining.hs b/src/Network/Bitcoin/Mining.hs
--- a/src/Network/Bitcoin/Mining.hs
+++ b/src/Network/Bitcoin/Mining.hs
@@ -47,9 +47,9 @@
                          --   available cores, and any other value to limit it.
             -> IO ()
 setGenerate auth onOff Nothing =
-    callApi auth "setgenerate" [ tj onOff ]
+    unNil <$> callApi auth "setgenerate" [ tj onOff ]
 setGenerate auth onOff (Just limit) =
-    callApi auth "setgenerate" [ tj onOff, tj limit ]
+    unNil <$> callApi auth "setgenerate" [ tj onOff, tj limit ]
 
 -- | Returns a recent hashes per second performance measurement while
 --   generating.
diff --git a/src/Network/Bitcoin/Wallet.hs b/src/Network/Bitcoin/Wallet.hs
--- a/src/Network/Bitcoin/Wallet.hs
+++ b/src/Network/Bitcoin/Wallet.hs
@@ -108,7 +108,7 @@
                                         <*> o .:  "proxy"
                                         <*> o .:  "difficulty"
                                         <*> o .:  "testnet"
-                                        <*> o .:  "keypoololddest"
+                                        <*> o .:  "keypoololdest"
                                         <*> o .:  "keypoolsize"
                                         <*> o .:  "paytxfee"
                                         <*> o .:? "unlocked_until"
@@ -417,11 +417,11 @@
              -> FilePath
              -> IO ()
 backupWallet auth fp =
-    callApi auth "backupwallet" [ tj fp ]
+    unNil <$> callApi auth "backupwallet" [ tj fp ]
 
 -- | Fills the keypool.
 keyPoolRefill :: Auth -> IO ()
-keyPoolRefill auth = callApi auth "keypoolrefill" []
+keyPoolRefill auth = unNil <$> callApi auth "keypoolrefill" []
 
 -- | Stores the wallet decryption key in memory for the given amount of time.
 unlockWallet :: Auth
@@ -431,7 +431,7 @@
              -- ^ How long to store the key in memory (in seconds).
              -> IO ()
 unlockWallet auth pass timeout =
-    callApi auth "walletpassphrase" [ tj pass, tj timeout ]
+    unNil <$> callApi auth "walletpassphrase" [ tj pass, tj timeout ]
 
 -- | Changes the wallet passphrase.
 changePassword :: Auth
@@ -441,7 +441,7 @@
                -- ^ The new password.
                -> IO ()
 changePassword auth old new =
-    callApi auth "walletpassphrase" [ tj old, tj new ]
+    unNil <$> callApi auth "walletpassphrase" [ tj old, tj new ]
 
 -- | Removes the wallet encryption key from memory, locking the wallet.
 --
@@ -451,7 +451,7 @@
 --   Note: In future releases, we might introduce an "unlocked" monad, so
 --         locking and unlocking is automatic.
 lockWallet :: Auth -> IO ()
-lockWallet auth = callApi auth "walletlock" []
+lockWallet auth = unNil <$> callApi auth "walletlock" []
 
 -- | Encrypts the wallet with the given passphrase.
 --