--- a/browser/components/preferences/in-content/tests/browser_extension_controlled.js
+++ b/browser/components/preferences/in-content/tests/browser_extension_controlled.js
@@ -269,16 +269,18 @@ add_task(async function testExtensionCon
   doc.getElementById("disableNewTabExtension").click();
 
   await waitForMessageHidden("browserNewTabExtensionContent");
 
   ok(!aboutNewTabService.newTabURL.startsWith("moz-extension:"), "new tab page is set back to default");
   is(controlledContent.hidden, true, "The extension controlled row is hidden");
 
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
+  let addon = await AddonManager.getAddonByID("@set_newtab");
+  addon.uninstall();
 });
 
 add_task(async function testExtensionControlledHomepageUninstalledAddon() {
   async function checkHomepageEnabled() {
     await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
     let doc = gBrowser.contentDocument;
     is(gBrowser.currentURI.spec, "about:preferences#general",
       "#general should be in the URI for about:preferences");