Cable TV networks have found a new way to stuff more commercials into reruns of old TV shows and movies without extending the run time: they’re literally speeding them up.

Networks TBS and TNT have used compression technology to shorten programming, Wall Street Journal reports. TBS has sped up crowd pleasers from Seinfeld reruns to the movie The Wizard of Oz, and TNT has done the same with Friends. The most discernible impact on the viewer is that the characters’ voices are a notch higher.

Friends co-creator Marta Kauffman said of the practice: “It feels wrong. It is not how it was shot, written or imagined. It wasn’t meant to be that way, so don’t make it that way.”

But the networks are trying to offset shrinking ad revenue. “It is a way to keep the revenue from going down as much as the ratings,” one top executive at a major cable programmer told the WSJ. “The only way we can do it is to double down and stretch the unit load a little more.”

According to Nielsen, the average commercial time on cable TV per hour has increased to 15.8 minutes in 2014 from 14.5 minutes five years ago, with networks such as MTV, TV Land and Spike now containing over 20 minutes of non-programming content an hour.