Ask HN: How can I make sure no one will steal my work on Github?

I've finally decided I need to publish some of my past projects on Github to show off my work to potential employers. But how can I make sure that no one else will steal it and claim it as their own work?

I'm going to add a license to it, I just haven't looked into the right one, but if I make it a public repository on Github then how can I prevent someone from copy-pasting the code and claiming they wrote it?