Comcast should stop saying in advertisements that it “delivers the fastest Internet in America” and the “fastest in-home Wi-Fi,” according to the advertising industry’s self-regulation body. The evidence Comcast uses to substantiate those claims is not sufficient, ruled the National Advertising Review Board (NARB).

Verizon had challenged Comcast’s advertising claims, leading to today’s ruling. Comcast said today that it disagreed with the findings but will comply with the decision.

Comcast used crowdsourced speed test data from Ookla to make its claim about Xfinity Internet speeds.