This paper reports on our experience in automatically migrating the crosscutting concerns of a large-scale software system, written in C, to an aspect-oriented implementation. We present a systematic approach for isolating crosscutting concerns, and illustrate this approach by zooming in on one particular crosscutting concern. Additionally, we compare the already existing solution to the aspect-oriented solution, and discuss advantages as well as disadvantages of both in terms of selected quality attributes. Our results show that automated migration is feasible, and that adopting an aspect-oriented approach can lead to significant improvements in source code quality, if carefully designed and managed.