[Haskell-beginners] Can't square zero as a complex number?

Hi, Is there a reason why I can't use ** to square zero as a complex number? Prelude> :m Data.Complex Prelude Data.Complex> (0:+0) ** 2 NaN :+ NaN Prelude Data.Complex> (0 :: Complex Double) ** 2 NaN :+ NaN Using GHC 7.4.1. Thanks, Scott