In its ongoing battle with Microsoft Teams, Slack has scored two major wins as SiriusXM and Uber have both deployed the messaging app to their employees.

Microsoft Teams recently doubled Slack’s user base, helped by the app’s deep integration with the rest of Office. Slack has maintained, however, that its users are more engaged and shot down concerns that it couldn’t effectively compete with Microsoft. Underscoring Slack’s claims, it has been scoring a number of significant wins, including IBM and now SiriusXM and Uber.

“Collaboration is key to our success, which is why we decided to use Slack as part of our efforts to bring our employees together,” said Bill Pratt, SVP and CIO at SiriusXM. “We see Slack as an important day-to-day productivity tool for our organization.”

Similarly, according to tweets by Uber employees, it seems the ride-hailing company made the switch to Slack yesterday.

Given the size of the messaging market, there’s no reason Teams and Slack can’t both exist with a healthy user base. With Slack’s recent gains, the company obviously is doing well convincing users it is not only viable, but competitive.