Outlook sends me to Teams when I want to start a Zoom session

I use Outlook 2016 and often schedule Zoom sessions using Outlook's meetings function.  Recently, I have found that if I click on "Join Online" in the entry in my Outlook calendar for a meeting scheduled for a Zoom session, Outlook opens a Teams session rather than a Zoom session.
Is there a setting I can tweak in Outlook to prevent this?