Something didn’t smell right. Turned out it wasn’t.

An unfamiliar chemical smell emanating from a shipment of purported 3M N95 face masks helped reveal that the respirators were counterfeit. In all, agents from U.S. Customs and Border Protection at the Port of Chicago (CBP) seized 65,280 of the knock-off masks, which had a domestic value of $401,000 had they been legit.

Grammatical errors on packaging helped tip off federal agents that these masks coming in through the Port of Chicago were counterfeit.

Imported into Chicago from Colombia, the masks were bound for an unidentified company in Virginia.

“These counterfeit masks are extremely dangerous and provide a false sense of security to American consumers,” said Hans Leiterman, assistant area port director-Chicago. “Unfortunately, there is no shortage of bad actors out there trying to take advantage of consumers during a global pandemic.”

3M’s N95 masks have been in high demand during the COVID-19 pandemic because they’re effective in helping to prevent the spread of the virus. Would-be scammers have tried to capitalize by flooding the market with counterfeits.

3M, parent company of Top 40 supplier 3M/Promotional Markets (asi/91240), has been collaborating closely with law enforcement to identify fraud. That’s helped lead to the seizure of millions of bogus N95s.

As for the seizure of 65,000 masks in Chicago, which occurred the week of March 1, authorities said that in addition to the odd smell, agents were tipped off because there were grammatical errors on the packaging that alleged to be from 3M.

CBP import specialists determined the shipment of 3M masks infringed upon the 3M trademark and National Institute for Occupational Safety and Health (NIOSH) trademark.

“Throughout the past year, criminal enterprises exploited the COVID-19 pandemic to sell counterfeit, unapproved, unsafe PPE and pharmaceuticals, but CBP has remained focused on its mission to protect consumers, reduce trading costs, and promote a level playing field for American businesses,” the organization said in a statement.