Good news for workplace grouches: just because you appear to hate your job, doesn't mean your employer can fire you.

In an April 29 ruling, the National Labor Review Board decided that your right to be grumpy or sour-faced at work is protected by U.S. labor laws, and that employers cannot require workers to be positive at all times, Quartz reported.

The controversy.

The hearing pertained to a clause in the T-Mobile employee handbook, which stated "employees are expected to maintain a positive work environment by communicating in a manner that is conducive to effective working relationships with internal and external customers, clients, co-workers, and management," according to Quartz.

The Communications Workers of America union — which represents the company's customer service representatives, retail employees, and technicians — opposed the clause, which was determined to infringe on workers' rights to organize and voice complaints against their employers.

The power of positivity?

Workplace positive psychology purports that happy employees increase a business's productivity — many employers introduce events like company retreats, office happy hours with this philosophy in mind.

"According to many reports, employees who feel satisfied, valued, and happy at work typically do far better than those who feel disgruntled or overlooked," the group WomensMedia stated, in a 2012 opinion piece on Forbes. "These findings have led many corporate officers to implement 'positive psychology' techniques in their workplaces."

The idea that positive company culture is good for business has been widely popularized in recent years, but the T-Mobile ruling makes the distinction that employers cannot implement rules that require employees to act positive.

"The key here is recognizing that being positive at work is good for business, but what’s good for business is not always good for labor," the Huffington Post reported about the ruling.

Why your boss can't force you to be upbeat.

The ruling mandated that forcing employees to appear chipper or upbeat infringes on workers rights to unionize and "join together to advance their interests as employees."

The NLRB explained:

“Because labor disputes and union organizing efforts frequently involve controversy, criticism of the employer, arguments, and less-than-‘positive’ statements about terms and conditions of employment, employees reading the rule here would reasonably steer clear of a range of potentially controversial but protected communication in the workplace for fear of running afoul of the rule."

Communications Workers of America spokesperson Candice Johnson said that the decision also “benefits non-represented workers who want a union," according to Quartz.

ATTN: reached out to T-Mobile, who said they could not comment because the issue is pending litigation.