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:             1.8.0
+Version:             1.8.1
 Synopsis:            An interface to bitcoind.
 Description:
     This can be used to send Bitcoins, query balances, etc.  It
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
@@ -334,7 +334,7 @@
          -- ^ An optional transaction comment.
          -> IO TransactionID
 sendMany client acc amounts comm =
-    callApi client "sendmany" [ tj acc, tj $ AA amounts, tj comm ]
+    callApi client "sendmany" [ tj acc, tj $ AA amounts, tj (1 :: Int), tj comm ]
 
 -- TODO: createmultisig.
 --