Talk to you boss, and look at your contract (assuming you have one that covers this). Most will have some clause in there saying that if you use code that you c

Talk to you boss, and look at your contract (assuming you have one that covers this). Most will have some clause in there saying that if you use code that you created before your employment, by using it at work you're giving the University an unlimited and irrevocable license to use that code. In terms of saving your ass for the future, I'd put a note in the source of the file saying where it came from initially, and keeping a copy of the email from your boss saying that it's OK to use that code (and expressly acknowledging that it's your code that you wrote before being employed with them). Do watch out about transferring the other way, however - if you use these libraries and add to/modify them, you can't then add that new function to your "clean" version to use in the future (it belongs to the employer, even if you type it into your clean version off the clock). Also check the part of your contract/clarify with your manager about what happens to code you write for personal projects while employed - some companies have especially onerous policies about them owning that code, even if you weren't at work when you wrote it.