ofxTrueTypeFontUC compile error "linuxFontPathByName" not declared

Hi there,
this message appears during compilation of some earlier work that had been compiled (successfully!) with OF 0.8.1.
now I am trying to compile it with of 0.8.4 and I get this error. in

…/…/…/addons/ofxTrueTypeFontUC/src/ofxTrueTypeFontUC.cpp|540|error: ‘linuxFontPathByName’ was not declared in this scope|

I created a new project, copied the sources, updated the addons.make and recompiled. This is the error I am stuck with.

any ideas?