markdown environment inside beamer frame

[Ninlives]

The following snippet will not work:

\begin{frame}
\begin{markdown}
- A markdown list
\end{markdown}
\end{frame}

and end with the following error:

Runaway argument?
! Paragraph ended before ^^M was complete.
<to be read again>
                   \par
l.69 \end{frame}
?
! Emergency stop.
<to be read again>
                   \par
l.69 \end{frame}

Why is that? I'm unfamiliar with latex internals and I'm not sure what is going on here...