--- a/browser/base/content/test/general/browser_bug431826.js
+++ b/browser/base/content/test/general/browser_bug431826.js
@@ -1,20 +1,16 @@
 function remote(task) {
   return ContentTask.spawn(gBrowser.selectedBrowser, null, task);
 }
 
 add_task(function* () {
   gBrowser.selectedTab = gBrowser.addTab();
 
-  let promise = remote(function() {
-    return ContentTaskUtils.waitForEvent(this, "DOMContentLoaded", true, event => {
-      return content.document.documentURI != "about:blank";
-    }).then(() => 0); // don't want to send the event to the chrome process
-  });
+  let promise = BrowserTestUtils.waitForErrorPage(gBrowser.selectedBrowser);
   gBrowser.loadURI("https://nocert.example.com/");
   yield promise;
 
   yield remote(() => {
     // Confirm that we are displaying the contributed error page, not the default
     let uri = content.document.documentURI;
     Assert.ok(uri.startsWith("about:certerror"), "Broken page should go to about:certerror, not about:neterror");
   });
@@ -25,19 +21,17 @@ add_task(function* () {
     Assert.ok(div, "Advanced content div should exist");
     Assert.equal(div.ownerGlobal.getComputedStyle(div).display,
       "none", "Advanced content should not be visible by default");
   });
 
   // Tweak the expert mode pref
   gPrefService.setBoolPref("browser.xul.error_pages.expert_bad_cert", true);
 
-  promise = remote(function() {
-    return ContentTaskUtils.waitForEvent(this, "DOMContentLoaded", true);
-  });
+  promise = BrowserTestUtils.waitForErrorPage(gBrowser.selectedBrowser);
   gBrowser.reload();
   yield promise;
 
   yield remote(() => {
     let div = content.document.getElementById("badCertAdvancedPanel");
     Assert.ok(div, "Advanced content div should exist");
     Assert.equal(div.ownerGlobal.getComputedStyle(div).display,
       "block", "Advanced content should be visible by default");