If you decide to complain to your manager, make sure you couch it in the most specific, quantifiable terms possible. Here are some tips.

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You like your job. And, for the most part, you like the people you work with — except for that one dude.

You know the one I mean. He (or she) consistently shows up late or not at all. Or when he’s there, he’s not really there. Promises are broken, deadlines are missed, performance is sloppy. Too often. If all this didn’t have an impact on your own projects and deadlines, you might not care. But it does.

You’ve tried talking with the slacker. You’ve explained the negative impact his or her behavior has on the rest of the team. You’ve even offered to help, generously assuming that the problem stems from poor training, lack of experience, lack of skills or even issues at home.

Alas, none of this has helped. Moreover, you and your colleagues are tired of covering for this person. It’s time to take the issue to the higher-ups. However, before you take this step, you need to plan your approach with care. You know that old expression, “Shoot the messenger”? You do not want this to happen to you.

So make sure you couch your complaint in the most specific, quantifiable terms possible. Show how the problem co-worker’s behavior harms the company’s bottom line. Instead of saying “Fred is a slacker,” say, “We can go no further with this project because Fred has not done his part.” Or “We missed the deadline because Fred has left work early every day for the past five days.” Or “I have had to put off customers’ requests because I am so busy doing Fred’s work.” Share all this info in private, at a time convenient for your manager.

Use facts. Be dispassionate. Remain upbeat. Avoid personal judgments. Don’t assume that your manager doesn’t already know about this problem, but don’t assume anything is being done about it, either. Truth is, management doesn’t enjoy dealing with personnel issues any more than you do.

Plopping a problem on management’s doorstep is always tricky. Nobody likes a tattletale! Once you have delivered the message, return to doing your usual excellent work. Try not to get caught up in issues of fairness. Make sure your behavior clearly demonstrates goodwill, and a willingness to go the extra mile.

And whatever you do, don’t let your co-worker’s slacker ways rub off on you.

Karen Burns is the author of The Amazing Adventures of Working Girl: Real-Life Career Advice You Can Actually Use. Email her at wg@karenburnsworkinggirl.com.