Every codebase had those dark, unkept, fragile corners, anxiety inducing we like to avoid and sometimes we just tip toe around to fix issues without touching anything else. I usually try and follow the scout rule, always leave a place cleaner than you found it, and this applies to codebases as well.

If you do this repeatedly, you will be raising the bar on code quality for your codebase and making it easier for your future self and others.