What’s the number one thing you should never do in a job interview? Check your phone, according to new research from The Creative Group, a specialized staffing service for interactive, design, marketing, advertising and public relations professionals.

According to a press release, checking your phone is the top way a candidate can blow their chances, according to a survey of marketing and advertising executives, with more than three quarters (77%) saying they would likely remove the candidate from consideration if the person used their phone during the interview.

The survey was conducted by an independent research firm and is based on 400 telephone interviews. Advertising and marketing executives were asked, “When interviewing candidates for creative roles, which of the following do you consider to be a deal breaker (something a candidate says or does that will likely cause you to immediately discount that person from consideration)?” Their responses:

    Checking or answering the phone during the interview: 77%
    Showing up late without acknowledging it: 70%
    Not bringing items that were requested (e.g., resume, portfolio, references): 70%
    Wearing improper interview attire: 69%
    Speaking poorly of a past job or employer: 62%

“Hiring managers typically assume candidates are putting their best foot forward during job interviews, so any sign of unprofessional or unproductive behavior makes a big impact, no matter how qualified the person may be for the position,” Diane Domeyer, executive director of The Creative Group, is quoted as sying. “Job seekers should do everything they can to tip the scales in their favor, including paying attention to the smallest details.”

In other words, if you’re checking your phone and showing up late when you’re on your best behaviour, what will you do when you relax?

Another recent survey found that one third of millennials think it’s acceptable to text during a job interview. So, if you know a millennial, do them a solid and pass this information along.