wrong spacing above caption w/ floatrow + longtable

Hi,

When using caption + floatrow + longtable, caption incorrectly adds "skip" before the caption in longtables if the caption is at the top. A MWE:

\documentclass{book}

% Comment/uncomment this to see the issue
\usepackage{floatrow}
\usepackage{array,longtable,mwe,caption}

% "position=top" has no effect
\captionsetup[longtable]{position=top}

\begin{document}

A text line.

\begin{longtable}{m{.9\textwidth}}

\caption{A caption}\\
\endfirsthead

A table cell\\

\end{longtable}

\end{document}

There is a simple workaround: just add \captionsetup[longtable]{skip=0pt}.

Thanks!