diff --git a/browser/components/resistfingerprinting/test/browser/browser_bug1369357_site_specific_zoom_level.js b/browser/components/resistfingerprinting/test/browser/browser_bug1369357_site_specific_zoom_level.js
index b11ea22631b7..ee77494e1816 100644
--- a/browser/components/resistfingerprinting/test/browser/browser_bug1369357_site_specific_zoom_level.js
+++ b/browser/components/resistfingerprinting/test/browser/browser_bug1369357_site_specific_zoom_level.js
@@ -25,6 +25,8 @@ add_task(async function() {
 
   isnot(tab3Zoom, tab1Zoom, "privacy.resistFingerprinting is true, site-specific zoom level should be disabled");
 
+  await FullZoom.reset();
+
   BrowserTestUtils.removeTab(tab1);
   BrowserTestUtils.removeTab(tab2);
   BrowserTestUtils.removeTab(tab3);
diff --git a/browser/components/resistfingerprinting/test/browser/browser_dynamical_window_rounding.js b/browser/components/resistfingerprinting/test/browser/browser_dynamical_window_rounding.js
index ea261b7820d7..ae8055a49ce5 100644
--- a/browser/components/resistfingerprinting/test/browser/browser_dynamical_window_rounding.js
+++ b/browser/components/resistfingerprinting/test/browser/browser_dynamical_window_rounding.js
@@ -4,6 +4,10 @@
  *
  * Bug 1407366 - A test case for reassuring the size of the content viewport is
  *   rounded if the window is resized when letterboxing is enabled.
+ *
+ * A helpful note: if this test starts randomly failing; it may be because the
+ * zoom level was not reset by an earlier-run test. See Bug 1407366 for an
+ * example.
  */
 
 const TEST_PATH = "http://example.net/browser/browser/components/resistfingerprinting/test/browser/";