--- a/browser/base/content/test/newtab/browser.ini
+++ b/browser/base/content/test/newtab/browser.ini
@@ -23,16 +23,17 @@ skip-if = (os == "mac" && debug) # tempo
 [browser_newtab_bug1271075.js]
 [browser_newtab_disable.js]
 [browser_newtab_drag_drop.js]
 [browser_newtab_drag_drop_ext.js]
 # temporary until determine why more intermittent on VM
 subsuite = clipboard
 [browser_newtab_drop_preview.js]
 [browser_newtab_focus.js]
+[browser_newtab_fullscreen_focus.js]
 [browser_newtab_perwindow_private_browsing.js]
 [browser_newtab_reflow_load.js]
 support-files =
   content-reflows.js
 [browser_newtab_search.js]
 support-files =
   searchEngineNoLogo.xml
   searchEngineFavicon.xml

new file mode 100644
--- /dev/null
+++ b/browser/base/content/test/newtab/browser_newtab_fullscreen_focus.js
@@ -0,0 +1,35 @@
+"use strict";
+
+function isFullscreenSizeMode() {
+  let sizemode = document.documentElement.getAttribute("sizemode");
+  return sizemode == "fullscreen";
+}
+
+/**
+ * Checks that the URL bar is correctly focused
+ * when a new tab is opened while in fullscreen
+ * mode.
+ */
+add_task(async function() {
+  gURLBar.blur();
+
+  Assert.ok(!window.fullScreen, "Should not start in fullscreen mode.");
+  BrowserFullScreen();
+  await BrowserTestUtils.waitForCondition(() => isFullscreenSizeMode());
+
+  registerCleanupFunction(async function() {
+    // Exit fullscreen if we're still in it.
+    if (window.fullScreen) {
+      BrowserFullScreen();
+      await BrowserTestUtils.waitForCondition(() => !isFullscreenSizeMode());
+    }
+  });
+
+  Assert.ok(window.fullScreen, "Should be in fullscreen mode now.");
+
+  let newTabOpened = BrowserTestUtils.waitForEvent(gBrowser, "TabSwitchDone");
+  BrowserOpenTab();
+  await newTabOpened;
+
+  Assert.ok(gURLBar.focused, "URL bar should be focused.");
+});