You’re in an interview for the job of your dreams. It’s going well, but don’t get too excited yet. Remember that the job isn’t yours until you and your employer have both signed on the dotted line.

Here are common mistakes that can ruin your chances of landing that great job:

1. Lying about other job offers

When you really have another job offer elsewhere, then it’s OK to mention it in hopes of improving the salary offer or closing the deal sooner. Tell the company where you really want the job that you are holding out for their offer, but that you need to decide soon because another company is also waiting for your answer.

When you don’t actually have a job offer, don’t lie about it. You may be caught in the lie, or worse, the company you really want the job with decides to go for someone else, leaving you without options.

2. Over-negotiating

Don’t negotiate just for the sake of negotiating. This gives employers the impression that you are difficult or inflexible. Learn to know when to let go, and call it a day. Remember, negotiating means that someone (or something) has got to give.

Negotiate for a fair pay and benefits package according to what you can bring to the table, but don’t left your future employer think that you’re milking them dry.

3. Giving an ultimatum

Remember that the job isn’t yours yet, and that you are in no place to offer an ultimatum. Negotiating a job offer is a collaborative process. Treat the hiring manager with respect, and remember that the person you are negotiating with may very well be your future boss.

If you say that you can only accept a job offer if certain conditions are met, you may prove yourself too difficult a person to work with and the company may seek a new employee elsewhere. Be ready to negotiate, and be flexible and make sure that you and your requests are fair and reasonable.

4. Lying about previous salary

Don’t lie about your previous salary to inflate the offer at a potential job. Some employers will ask to check an old paystub, and if you are caught, it could cost you a job offer.

5. Not warning your references that a new employer might be calling

Tell your references that a new employer might be calling them, and tell them what the new job entails so that they are ready to discuss it with whoever is conducting the background check. That way, everything goes as smoothly as possible. Your new hiring manager will appreciate it, and your references will feel better prepared to discuss your past work.