Don’t be a jerk. Stop ending your texts with periods.

The period is dead. Punctuation is over. Run-on sentences and incomplete thoughts are the new standard. Do I sound insincere? Maybe it’s because proper grammar is now being associated with insincerity, at least when it comes to texting.

As it turns out, science has now confirmed that your passive-aggressive habit of ending one-word texts with periods to quietly express your anger (“k.” “fine.” “cool.”) isn’t as passive as you think. According to new research published in the journal Computers in Human Behavior, texts that end with a period are rated as less sincere than those that do not. Great.

Led by Binghamton University’s Celia Klin, a team of researchers asked a group of 126 college undergrads (a small sample size, to be sure, but likely quite representative of the most active texting demographic) to look at a series of both texts and handwritten notes. Common one-word responses like “yeah,” “sure,” “ok,” and the like were shown with and without periods. When participants were asked to judge the degree of sincerity of these notes, the researchers found that “the responses that ended with a period were rated as less sincere than those that did not end with a period.” However, this same discrepancy was not observed in handwritten notes.

“We conclude that punctuation is one cue used by senders, and understood by receivers, to convey pragmatic and social information,” wrote Klin’s team.

So one seemingly harmless piece of punctuation has now been loaded with (often negative) meaning. Connotation no longer applies only to words, but in how you choose to end them as well. “Texting is lacking many of the social cues used in actual face-to-face conversations,” Klin said in a statement. “When speaking, people easily convey social and emotional information with eye gaze, facial expressions, tone of voice, pauses, and so on.”

But the same isn’t true with texting. And given the rapidity with which we often send these short messages, taking the extra time to put a period at the end of an otherwise cursory message does seem to affect how the message is received. “Texters rely on what they have available to them  — emoticons, deliberate misspellings that mimic speech sounds and, according to our data, punctuation,” Klin noted.

That isn’t to say that no punctuation is always better. In unpublished research, Klin’s team has found that the use of exclamation marks often makes the texter seem more sincere (though maybe there’s a limit on how many of those you can slap onto a sentence before sounding snarky). And of course, there’s no word yet on whether grandma (or your other older relatives), who was raised on oxford commas, means to come off rudely when she sends you a text that reads, “Love you.”

But look out millennials — science is onto you. And now we know what “thanks.” really means.