--- a/browser/extensions/moz.build
+++ b/browser/extensions/moz.build
@@ -4,9 +4,10 @@
 # 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/.
 
 DIRS += [
     'e10srollout',
     'pdfjs',
     'pocket',
     'webcompat',
+    'websensehelper',
 ]

copy from browser/extensions/webcompat/bootstrap.js
copy to browser/extensions/websensehelper/bootstrap.js
--- a/browser/extensions/webcompat/bootstrap.js
+++ b/browser/extensions/websensehelper/bootstrap.js
@@ -1,10 +1,61 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* 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/. */
 
-// for now we ship a stub, that can be upgraded as-needed after release
-function startup() {}
+const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
+
+const APP_UPDATE_URL_PREF = "app.update.url";
+const REPLACE_KEY = "%OS_VERSION%";
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/osfile.jsm");
+Cu.import("resource://gre/modules/TelemetryLog.jsm");
+
+function startup() {
+  if (Services.appinfo.OS != "WINNT") {
+    return;
+  }
+
+  try {
+    let windir = Services.dirsvc.get("WinD", Ci.nsILocalFile).path;
+
+    let file1 = OS.Path.join(windir, "System32\\qipcap.dll");
+    let file2 = OS.Path.join(windir, "System32\\qipcap64.dll");
+    let file3 = OS.Path.join(windir, "sysnative\\qipcap.dll");
+    let file4 = OS.Path.join(windir, "sysnative\\qipcap64.dll");
+
+    let existPromises = [
+      OS.File.exists(file1),
+      OS.File.exists(file2),
+      OS.File.exists(file3),
+      OS.File.exists(file4)
+    ];
+
+    // Update the app.update.url pref to include a special mark
+    // telling whether any of those files are present or not.
+    Promise.all(existPromises).then(results => {
+      let newValue = "(nowebsense)";
+
+      if (results.some(value => value == true)) {
+        newValue = "(websense)";
+      }
+
+      let branch = Services.prefs.getDefaultBranch("");
+      let curValue = branch.getCharPref(APP_UPDATE_URL_PREF);
+      newValue = curValue.replace(REPLACE_KEY + "/", REPLACE_KEY + newValue + "/");
+      branch.setCharPref(APP_UPDATE_URL_PREF, newValue);
+
+    }, reject => {
+      Cu.reportError("Hotfix unexpected error: " + reject);
+      TelemetryLog.log("WEBSENSE_PROMISE_ERROR", [reject]);
+    });
+  } catch (ex) {
+    Cu.reportError(ex);
+    TelemetryLog.log("WEBSENSE_DETECTION_ERROR", [ex]);
+  }
+}
+
 function shutdown() {}
 function install() {}
 function uninstall() {}

copy from browser/extensions/webcompat/install.rdf.in
copy to browser/extensions/websensehelper/install.rdf.in
--- a/browser/extensions/webcompat/install.rdf.in
+++ b/browser/extensions/websensehelper/install.rdf.in
@@ -4,28 +4,28 @@
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
 #filter substitution
 
 <RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
      xmlns:em="http://www.mozilla.org/2004/em-rdf#">
 
   <Description about="urn:mozilla:install-manifest">
-    <em:id>webcompat@mozilla.org</em:id>
+    <em:id>websensehelper@mozilla.org</em:id>
     <em:version>1.0</em:version>
     <em:type>2</em:type>
     <em:bootstrap>true</em:bootstrap>
 
     <!-- Target Application this theme can install into,
         with minimum and maximum supported versions. -->
     <em:targetApplication>
       <Description>
         <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
         <em:minVersion>@MOZ_APP_VERSION@</em:minVersion>
         <em:maxVersion>@MOZ_APP_MAXVERSION@</em:maxVersion>
       </Description>
     </em:targetApplication>
 
     <!-- Front End MetaData -->
-    <em:name>Web Compat</em:name>
-    <em:description>Urgent post-release fixes for web compatibility.</em:description>
+    <em:name>Websense Helper</em:name>
+    <em:description>Checks for the non-presence of Websense to allow updates to happen.</em:description>
   </Description>
 </RDF>

copy from browser/extensions/webcompat/moz.build
copy to browser/extensions/websensehelper/moz.build
--- a/browser/extensions/webcompat/moz.build
+++ b/browser/extensions/websensehelper/moz.build
@@ -2,17 +2,15 @@
 # vim: set filetype=python:
 # 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/.
 
 DEFINES['MOZ_APP_VERSION'] = CONFIG['MOZ_APP_VERSION']
 DEFINES['MOZ_APP_MAXVERSION'] = CONFIG['MOZ_APP_MAXVERSION']
 
-FINAL_TARGET_FILES.features['webcompat@mozilla.org'] += [
+FINAL_TARGET_FILES.features['websensehelper@mozilla.org'] += [
   'bootstrap.js'
 ]
 
-FINAL_TARGET_PP_FILES.features['webcompat@mozilla.org'] += [
+FINAL_TARGET_PP_FILES.features['websensehelper@mozilla.org'] += [
   'install.rdf.in'
 ]
-
-BROWSER_CHROME_MANIFESTS += ['test/browser.ini']