diff --git a/bitcoin-payment-channel.cabal b/bitcoin-payment-channel.cabal
--- a/bitcoin-payment-channel.cabal
+++ b/bitcoin-payment-channel.cabal
@@ -1,5 +1,5 @@
 name:                 bitcoin-payment-channel
-version:              0.1.1.0
+version:              0.1.1.1
 synopsis:             Library for working with Bitcoin payment channels
 description:
     A Bitcoin payment channel allows two parties two send value to each other very rapidly.
@@ -45,12 +45,12 @@
 
 --  ghc-options:          -Wall
 
-  build-depends:        base,
+  build-depends:        base >= 4.7 && < 5,
+                        haskoin-core >= 0.3.0 && < 1.0.0,
                         bytestring, text, base16-bytestring, base58string, hexstring,
                         base64-bytestring,
                         time,
-                        cereal, binary, aeson, scientific,
-                        haskoin-core
+                        cereal, binary, aeson, scientific
   hs-source-dirs:       src
 
   default-language:     Haskell2010
@@ -65,11 +65,12 @@
 --  ghc-options:          -Wall
 
   build-depends:        base >= 4.7 && < 5,
-                        bytestring, text, base16-bytestring, base58string, hexstring,
-                        base64-bytestring,
+                        haskoin-core >= 0.3.0 && < 1.0.0,
+                        bytestring, base16-bytestring, base64-bytestring,
+                        base58string, hexstring, text,
                         time,
                         cereal, binary, aeson,
-                        haskoin-core,
+
                         QuickCheck,
                         bitcoin-payment-channel
 
diff --git a/src/Data/Bitcoin/PaymentChannel.hs b/src/Data/Bitcoin/PaymentChannel.hs
--- a/src/Data/Bitcoin/PaymentChannel.hs
+++ b/src/Data/Bitcoin/PaymentChannel.hs
@@ -152,7 +152,7 @@
             Right newCS ->
                 (payment
                 ,CSenderPaymentChannel newCS signFunc)
-            Left _ -> error "BUG #3: sendPayment should not be able to rewind payments"
+            Left _ -> error "BUG: 'createPayment' created value-backtracking tx"
 
 -- |Produces a Bitcoin transaction which sends all channel funds back to the sender.
 -- Will not be accepted by the Bitcoin network until the expiration time specified in
diff --git a/src/Data/Bitcoin/PaymentChannel/Internal/Util.hs b/src/Data/Bitcoin/PaymentChannel/Internal/Util.hs
--- a/src/Data/Bitcoin/PaymentChannel/Internal/Util.hs
+++ b/src/Data/Bitcoin/PaymentChannel/Internal/Util.hs
@@ -136,7 +136,7 @@
 parseBitcoinLocktime i
     | i <   500000000 = LockTimeBlockHeight i
     | i >=  500000000 = LockTimeDate $ posixSecondsToUTCTime (fromIntegral i)
-    | otherwise       = error "BUG"
+    | otherwise       = error "BUG (in GHC?)"
 
 -- | Convert to Bitcoin format ('Word32')
 toWord32 :: BitcoinLockTime -> Word32
diff --git a/src/Data/Bitcoin/PaymentChannel/Util.hs b/src/Data/Bitcoin/PaymentChannel/Util.hs
--- a/src/Data/Bitcoin/PaymentChannel/Util.hs
+++ b/src/Data/Bitcoin/PaymentChannel/Util.hs
@@ -13,6 +13,7 @@
 getFundingAddress,
 setSenderChangeAddress,
 
+serialize, serialize',
 BitcoinLockTime, parseBitcoinLocktime, toWord32, fromDate, deserEither
 )
 where
@@ -24,7 +25,7 @@
 import Data.Bitcoin.PaymentChannel.Internal.Script
     (getP2SHFundingAddress)
 import Data.Bitcoin.PaymentChannel.Internal.Util
-    (BitcoinLockTime, parseBitcoinLocktime, toWord32, fromDate, deserEither)
+    (BitcoinLockTime, parseBitcoinLocktime, toWord32, fromDate, deserEither, serialize, serialize')
 import Data.Bitcoin.PaymentChannel.Internal.State
     (setClientChangeAddress)