Last week, Microsoft revealed that it has more than 13 million users for its Microsoft Teams chat software meaning the app has surpassed Slack. But Slack founder and CEO Stewart Butterfield isn’t worried at all.

While appearing as a speaker in the Brainstorm Tech 2019 business conference on Monday, the CEO says he doesn’t think of Microsoft Teams’ achievement as a threat.

“If it’s based on the bigger distribution [Office 365], I don’t think that’s really a threat,” Butterfield said according to CNBC.

Butterfield cited the tech giant’s failed efforts to compete with Google’s search engine with Bing. “Tens of billions of dollars into that [search engine] and I don’t know what their market share is now — 9 percent or something like that,” the tech exec said. He also noted how Google+ failed despite its effort to be bundled with other Google services.

Microsoft is bundling its Microsoft Teams software with its popular Office 365 service into its business offers which means active user numbers don’t necessarily determine its success. At present, Slack has over 88,000 paid plan subscriptions but more than 500,000 organization are still using the service’s free plan.

As for Microsoft, it has recently pulled a gimmick that received backlash from partners. In its Inspire partner conference in Las Vegas, thousands of attendees were given a free cup of Starbucks coffee in exchange for downloading the Microsoft Teams mobile up during the keynote address. Licensing changes for the app angered partners and it was quickly reversed. The company has since offerea free “Microsoft Inspire Cloud Macchiato” as an apology.