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The last time CBS won the ratings war for late-night programming, there was a Clinton in the White House and a guy named Leno in the driver’s seat over at NBC competing with someone named Letterman at CBS. After a relatively brief stay at the top of the heap, Leno overtook Letterman again and, with a few breaks, kept the top spot until he retired in 2009.

Last week, CBS finally climbed back to the number one spot in the late-night rankings with its “Late Show With Stephen Colbert.” It was not a take-no-prisoners type of win, but it was a win nonetheless.

Colbert’s show drew 3.195 million viewers last week, compared to 3.173 million for NBC’s “Tonight Show Starring Jimmy Fallon.” For the year to date, Colbert’s show has improved its ratings by 11%, while Fallon’s show has dropped by 15%. The other network competitor, ABC’s “Jimmy Kimmel Live!” has maintained around 2.2 million viewers steadily through the year.

Colbert took over the “Late Show” following Letterman’s retirement in 2015, and that first year was a struggle. Then Donald Trump was elected and inaugurated, and Colbert returned to the style of comedy he had become famous for with Jon Stewart’s “The Daily Show” and Colbert’s own “The Colbert Report,” both on Comedy Central.

Fallon’s “Tonight Show” continues to have the highest ratings among late night TV shows with the 18- to 34-year-old demographic segment. Even last week, when Colbert took the overall top spot, Fallon averaged a 0.68 rating compared to Colbert’s average rating of 0.52.

While the ratings report is good news for CBS Corp. (NYSE: CBS) and Colbert, it pays to remember that TV viewership is down, which means selling commercials to advertisers won’t pay all the bills anymore. But there is revenue for the networks in streaming clips, and it’s there that the politically pointed humor of Colbert may have a distinct advantage over Fallon who is seen more as a traditional comedian.

One win in 22 years is hardly a pattern, but all streaks have to start with a first win. And now that CBS has that, advertisers will want to see how long the network can keep the streak going.