diff --git a/browser/base/content/browser-plugins.js b/browser/base/content/browser-plugins.js
index 730d2cfdc7f..0918bc70008 100644
--- a/browser/base/content/browser-plugins.js
+++ b/browser/base/content/browser-plugins.js
@@ -106,8 +106,8 @@ var gPluginHandler = {
     let pluginRect = plugin.getBoundingClientRect();
     // XXX bug 446693. The text-shadow on the submitted-report text at
     //     the bottom causes scrollHeight to be larger than it should be.
-    let overflows = (overlay.scrollWidth > pluginRect.width) ||
-                    (overlay.scrollHeight - 5 > pluginRect.height);
+    let overflows = (overlay.scrollWidth > Math.ceil(pluginRect.width)) ||
+                    (overlay.scrollHeight - 5 > Math.ceil(pluginRect.height));
     if (overflows) {
       return false;
     }
diff --git a/browser/base/content/test/plugins/browser.ini b/browser/base/content/test/plugins/browser.ini
index 51f6ec9459c..cf659134768 100644
--- a/browser/base/content/test/plugins/browser.ini
+++ b/browser/base/content/test/plugins/browser.ini
@@ -40,6 +40,7 @@ support-files =
   plugin_two_types.html
   plugin_unknown.html
   plugin_crashCommentAndURL.html
+  plugin_zoom.html
 
 [browser_bug743421.js]
 [browser_bug744745.js]
@@ -62,6 +63,7 @@ run-if = crashreporter
 [browser_CTP_notificationBar.js]
 [browser_CTP_outsideScrollArea.js]
 [browser_CTP_resize.js]
+[browser_CTP_zoom.js]
 [browser_globalplugin_crashinfobar.js]
 [browser_pageInfo_plugins.js]
 [browser_pluginnotification.js]
diff --git a/browser/base/content/test/plugins/browser_CTP_zoom.js b/browser/base/content/test/plugins/browser_CTP_zoom.js
new file mode 100644
index 00000000000..6d351786ac9
--- /dev/null
+++ b/browser/base/content/test/plugins/browser_CTP_zoom.js
@@ -0,0 +1,77 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+let rootDir = getRootDirectory(gTestPath);
+const gTestRoot = rootDir;
+const gHttpTestRoot = rootDir.replace("chrome://mochitests/content/",
+                                      "http://127.0.0.1:8888/");
+
+let gTestBrowser = null;
+
+Components.utils.import("resource://gre/modules/Services.jsm");
+
+function test() {
+  waitForExplicitFinish();
+  registerCleanupFunction(() => {
+    FullZoom.reset();
+    clearAllPluginPermissions();
+    Services.prefs.clearUserPref("extensions.blocklist.suppressUI");
+  });
+  Services.prefs.setBoolPref("extensions.blocklist.suppressUI", true);
+
+  Services.prefs.setBoolPref("plugins.click_to_play", true);
+  setTestPluginEnabledState(Ci.nsIPluginTag.STATE_CLICKTOPLAY);
+
+  let newTab = gBrowser.addTab();
+  gBrowser.selectedTab = newTab;
+  gTestBrowser = gBrowser.selectedBrowser;
+  gTestBrowser.addEventListener("load", pageLoad, true);
+  gTestBrowser.contentWindow.location = gHttpTestRoot + "plugin_zoom.html"
+}
+
+function finishTest() {
+  clearAllPluginPermissions();
+  gTestBrowser.removeEventListener("load", pageLoad, true);
+  gBrowser.removeCurrentTab();
+  window.focus();
+  finish();
+}
+
+function pageLoad() {
+  // Due to layout being async, "PluginBindAttached" may trigger later.
+  // This wraps a function to force a layout flush, thus triggering it,
+  // and schedules the function execution so they're definitely executed
+  // afterwards.
+  let doc = gTestBrowser.contentDocument;
+  let elems = doc.getElementsByTagName('embed');
+  if (elems.length < 1) {
+    elems = doc.getElementsByTagName('object');
+  }
+  elems[0].clientTop;
+  executeSoon(testOverlay);
+}
+
+let enlargeCount = 4;
+
+// Enlarges the zoom level |enlargeCount| times and tests that the overlay is
+// visible after each enlargement.
+function testOverlay() {
+  let plugin = gTestBrowser.contentDocument.getElementById("test");
+  let doc = gTestBrowser.contentDocument;
+  let overlay = doc.getAnonymousElementByAttribute(plugin, "anonid", "main");
+  ok(overlay, "Overlay should exist");
+  ok(overlay.classList.contains("visible"), "Overlay should be visible");
+
+  if (enlargeCount > 0) {
+    --enlargeCount;
+    FullZoom.enlarge();
+    gTestBrowser.contentWindow.location.reload();
+  } else {
+    FullZoom.reset();
+    clearAllPluginPermissions();
+    finishTest();
+  }
+}
diff --git a/browser/base/content/test/plugins/plugin_zoom.html b/browser/base/content/test/plugins/plugin_zoom.html
new file mode 100644
index 00000000000..f9e5986581f
--- /dev/null
+++ b/browser/base/content/test/plugins/plugin_zoom.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+</head>
+<body>
+<!-- The odd width and height are here to trigger bug 972237. -->
+<embed id="test" style="width: 99.789%; height: 99.123%" type="application/x-test">
+</body>
+</html>