Using \refcmpd{a.one} inside of \ch{} prevents compiling

[Canageek]

Uncomment either line to prevent the document from compiling and reproduce the bug.

\documentclass{article}
\usepackage{chemmacros}
\chemsetup{formula=chemformula}
\usepackage[]{chemnum}

\begin{document}
\cmpd{a}
\cmpd{a.one}

\refcmpd{a}

\ch{\cmpd{a} -> c}

\ch{\refcmpd{a} -> c}

\refcmpd{a.one}

%\ch{\refcmpd{a.one} -> c} %If you uncomment this it stops compiling.
%\ch{\cmpd{a.one} -> c} %If you uncomment this it stops compiling.
\end{document}