How to stop sudo from timing out?

I update my Arch-Linux system using yaourt. When updating packages from the AUR, yaourt doesn't allow itself to be run as root, so it instead asks for sudo privileges every time it installs / updates a package. I don't mind this too much, however if I don't notice my terminal asking for my sudo password, it might be a few minutes until I check and notice it. When this happens, even though I type my password in correctly, I get an authentication error message, and it asks for my password again a few times, even though it still wouldn't work. So my question is: how can I disable the sudo password prompt from timing out?