When going on a job hunt, most people focus on their resume and interviews that they barely even think about who to name as their professional references. While an impressive resume and a solid interview will definitely help a person get employed, having the wrong people on your references list could cost you the job that you’ve been dreaming of.

You don’t need to include your references on your resume—you could have the list typed on a separate piece of paper and give it to your interviewer as needed. This will clue you in as to which company is seriously considering hiring you, and this way, you can also give your references a heads up on when they’ll call.

It’s very important to notify the people on your list regarding when the interviewer will call, as they could be unavailable for a few days. You can put a note on your reference list as to when is the best day and time to call them as a courtesy to your references.

But before making that list, here is a list of people you should never use as job references.

A person you don’t know

Many young people make the mistake of asking a friend to ask someone of importance to give them a reference. However, if this person doesn’t know you at all, he or she won’t be of much help when the interviewer calls, as the person does not have an idea of your work experience and the things that you’re capable of.

Rather than adding an impressive name to your references list, add someone who knows you well, preferably someone who has worked with you and knows your abilities. This person can be relied on to talk about your accomplishments and specific skills.

A boss you haven’t worked for in a very long time

If you add a supervisor or a boss whom you’ve worked for 10 years ago, chances are, he or she doesn’t have a clue with regards to your latest achievements and the skills that you have learned since you last worked for that person. However, if you have managed to stay in touch with your former boss and has kept that person in the loop regarding your career, then by all means, add him or her to the list.

Someone who fired you

According to The Muse, there’s no universal mandate that you have to use your most recent or any past supervisor as your reference—especially if that person fired you. There is a very strong possibility that this person won’t have anything good to say about you, so look for another supervisor or colleague who can vouch for you.

For more, check out Jobs & Hire’s report on the five things you should do as soon as you hand in your two weeks’ notice.