I never thought of `fromIntegral`... I'm still getting 

```
src/Network/Bitcoin/Wallet.hs:488:22:
    No instance for (Read POSIXTime)
      arising from the 'deriving' clause of a data type declaration
    Possible fix:
      add an instance declaration for (Read POSIXTime)
      or use a standalone 'deriving instance' declaration,
           so you can specify the instance context yourself
    When deriving the instance for (Read SimpleTransaction)

src/Network/Bitcoin/Wallet.hs:503:1:
    Can't make a derived instance of `Read POSIXTime':
      The data constructors of `NominalDiffTime' are not all in scope
        so you cannot derive an instance for it
    In the stand-alone deriving instance for `Read POSIXTime'
```

And if `import Data.Time.Clock.UTC` this 
```
src/Network/Bitcoin/Wallet.hs:76:8:
    Could not find module `Data.Time.Clock.UTC'
    it is a hidden module in the package `time-1.4.2'
    Use -v to see a list of the files searched for.
```