# “TeX capacity exceeded” because of a couple of raiseboxes in a \section?

In a package, I have the following command defined:

\newcommand\fkm{
\ensuremath{\mathrm{
\raisebox{-0.1ex}{\rotatebox{22}{f}}\!
\raisebox{0.2ex}{\rotatebox{-15} {k}}\!
m\!^{*}
}}
}

It works just as I'd expect in text, but if I say \section{\fkm} I get an error saying

! TeX capacity exceeded, sorry [input stack size=5000].

Why doesn't this work within sections? What can I do to make it work?

• Also, it doesn't seem to matter if I use the command (\section{\fkm}) or the code directly (\section{$\mathrm{...}$}) - I still get the error... – Tomas Aschan Oct 30 '10 at 19:50