--- a/browser/components/customizableui/test/browser_remote_tabs_button.js
+++ b/browser/components/customizableui/test/browser_remote_tabs_button.js
@@ -37,16 +37,18 @@ add_task(async function testSyncRemoteTa
   ok(syncRemoteTabsBtn, "The sync remote tabs button was added to the Panel Menu");
   // click the button - the panel should open.
   syncRemoteTabsBtn.click();
   await viewShown;
   ok(remoteTabsPanel.getAttribute("visible"), "Sync Panel is in view");
 
   // Find and click the "setup" button.
   let syncNowButton = document.getElementById("PanelUI-remotetabs-syncnow");
+  // A previous test may have triggered syncing.
+  await waitForCondition(() => !syncNowButton.disabled);
   syncNowButton.click();
   info("The sync now button was clicked");
 
   await waitForCondition(() => syncWasCalled);
 });
 
 add_task(async function asyncCleanup() {
   // reset the panel UI to the default state