Identifying employees that may be “at-risk” of becoming disgruntled or tempted to steal from the company can be hard to do, especially by co-workers that may not be paying attention to the right signs.

Here are six red flags that indicate you could have a problem employee already on staff, or a culture that’s not far from producing one.

1. Employees that don’t take vacation. Employees who have perfect attendance or never take days off are actually signs you might have someone with a problem.

2. They work odd hours. Someone working hours when other people generally aren’t in the office is potentially a problem and managers should find out why.

3. Employees that take a lot of work home. People going home with bundles of paperwork or other company information is a bit unusual in today’s times.

4. You’re hearing from debt collectors. Debt collectors are relentless, and the receptionist knows who at the company is getting calls from collection agencies.

5. Complaints of unfair pay. Watch out for employees that gripe over pay, and assess what access they have to payroll or other company financials.

6. Inconsistent accounting statements. Inconsistency in regular accounting reports and processes is typically a red flag and warrants more scrutiny.