TV networks have figured out how to game the Nielsen ratings system. It’s as easy as playing dumb, literally. On days when programmers know their viewership will drop, like on holiday weekends or during sporting events, they “accidentally” misspell their show’s name on the nightly Nielsen lineup, according to The Wall Street Journal.

Over the Friday of Memorial Day weekend, for example, NBC aired NBC Nitely News instead of its usual NBC Nightly News so the holiday drop in viewership didn’t affect its ratings standing. Nielsen’s automated system counted that misspelled show as an entirely different program. By doing this, NBC managed to actually gain ratings against its main competitor: ABC World News Tonight.

NBC apparently misspelled its shows 14 times since the start of the 2016 to 2017 TV season, and it’s not the only network to pull this tactic. This season, ABC did so seven times with its Wrld New Tonite, while CBS replaced The CBS Evening News with CBS Evening Nws 12 times. Clearly, this method isn’t much of a secret, although The Wall Street Journal points out that advertisers are catching on and are fed up with paying more for potentially disingenuous viewership counts.