Legacy code is the bane of most developers. Even so in C++ where you can find code that was created more than a decade ago. When a developer needs to add a feature or fix a bug in such codebase he's faced with a problem - how to add code to a mess without creating a bigger mess as well as additional bugs on the way? In this talk I show what worked for me when working with large, undocumented piles of C++ code, the practices and patterns that I use and how to transform unmaintainable code into code that can be extended and improved.