diff --git a/platform/chromium/manifest.json b/platform/chromium/manifest.json
index 358c372c7..0c8ea5b02 100644
--- a/platform/chromium/manifest.json
+++ b/platform/chromium/manifest.json
@@ -36,6 +36,15 @@
             "js": ["js/contentscript-end.js"],
             "run_at": "document_end",
             "all_frames": true
+        },
+        {
+            "matches": [
+                "https://*.adblockplus.org/*",
+                "https://*.adblockplus.me/*",
+                "https://www.fanboy.co.nz/*"
+            ],
+            "js": ["js/subscriber.js"],
+            "run_at": "document_idle"
         }
     ],
     "minimum_chrome_version": "22.0",
diff --git a/platform/firefox/frameModule.js b/platform/firefox/frameModule.js
index 3a16c70a7..cd513dc17 100644
--- a/platform/firefox/frameModule.js
+++ b/platform/firefox/frameModule.js
@@ -55,6 +55,11 @@ const contentObserver = {
     cpMessageName: hostName + ':shouldLoad',
     ignoredPopups: new WeakMap(),
     uniqueSandboxId: 1,
+    subscriberTargets: {
+        'adblockplus.org': true,
+        'adblockplus.me': true,
+        'fanboy.co.nz': true
+    },
 
     get componentRegistrar() {
         return Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
@@ -295,6 +300,27 @@ const contentObserver = {
         };
 
         subject.addEventListener('DOMContentLoaded', docReady, true);
+
+/* Does not work, I do not know why
+
+        let docIdle = function(e) {
+            this.removeEventListener(e.type, docIdle);
+            lss(this.contentBaseURI + 'subscriber.js', sandbox);
+        };
+
+        var target = loc.host;
+        while ( target !== '' ) {
+            if ( this.subscriberTargets.hasOwnProperty(target) ) {
+                subject.addEventListener('load', docIdle);
+                break;
+            }
+            let pos = target.indexOf('.');
+            if ( pos === -1 ) {
+                break;
+            }
+            target = target.slice(pos + 1);
+        }
+*/
     }
 };
 
diff --git a/src/_locales/en/messages.json b/src/_locales/en/messages.json
index 816bdbb7f..bb9a86f98 100644
--- a/src/_locales/en/messages.json
+++ b/src/_locales/en/messages.json
@@ -519,6 +519,10 @@
     "message":"Unable to connect to {{url}}",
     "description":"English: Network error: unable to connect to {{url}}"
   },
+  "subscriberConfirm":{
+    "message":"µBlock: Add the following resource to your selection of filter lists?\n\nTitle: \"{{title}}\"\nURL: {{url}}",
+    "description":"English: Network error: unable to connect to {{url}}"
+  },
   "dummy":{
     "message":"This entry must be the last one",
     "description":"so we dont need to deal with comma for last entry"
diff --git a/src/js/messaging.js b/src/js/messaging.js
index 30daad155..40d9e4517 100644
--- a/src/js/messaging.js
+++ b/src/js/messaging.js
@@ -19,7 +19,7 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-/* global µBlock, vAPI, YaMD5 */
+/* global µBlock, vAPI */
 
 /******************************************************************************/
 /******************************************************************************/
@@ -279,6 +279,7 @@ var onMessage = function(request, sender, callback) {
     }
 
     // Sync
+    var pageStore;
     var response;
 
     switch ( request.what ) {
@@ -290,7 +291,7 @@ var onMessage = function(request, sender, callback) {
             break;
 
         case 'hasPopupContentChanged':
-            var pageStore = µb.pageStoreFromTabId(request.tabId);
+            pageStore = µb.pageStoreFromTabId(request.tabId);
             var lastModified = pageStore ? pageStore.contentLastModified : 0;
             response = lastModified !== request.contentLastModified;
             break;
@@ -310,7 +311,7 @@ var onMessage = function(request, sender, callback) {
             break;
 
         case 'toggleNetFiltering':
-            var pageStore = µb.pageStoreFromTabId(request.tabId);
+            pageStore = µb.pageStoreFromTabId(request.tabId);
             if ( pageStore ) {
                 pageStore.toggleNetFilteringSwitch(request.url, request.scope, request.state);
                 µb.updateBadgeAsync(request.tabId);
@@ -666,9 +667,6 @@ var onMessage = function(request, sender, callback) {
         case 'purgeAllCaches':
             return µb.assets.purgeAll(callback);
 
-        case 'writeUserUbiquitousBlockRules':
-            return µb.assets.put(µb.userFiltersPath, request.content, callback);
-
         default:
             break;
     }
@@ -1133,3 +1131,47 @@ vAPI.messaging.listen('devtool-log.js', onMessage);
 // https://www.youtube.com/watch?v=3_WcygKJP1k
 
 /******************************************************************************/
+/******************************************************************************/
+
+// subscriber.js
+
+(function() {
+
+'use strict';
+
+/******************************************************************************/
+
+var onMessage = function(request, sender, callback) {
+    // Async
+    switch ( request.what ) {
+        default:
+            break;
+    }
+
+    // Sync
+    var response;
+
+    switch ( request.what ) {
+        case 'subscriberData':
+            response = {
+                confirmStr: vAPI.i18n('subscriberConfirm'),
+                externalLists: µBlock.userSettings.externalLists
+            };
+            break;
+
+        default:
+            return vAPI.messaging.UNHANDLED;
+    }
+
+    callback(response);
+};
+
+vAPI.messaging.listen('subscriber.js', onMessage);
+
+/******************************************************************************/
+
+})();
+
+// https://www.youtube.com/watch?v=3_WcygKJP1k
+
+/******************************************************************************/
diff --git a/src/js/storage.js b/src/js/storage.js
index cc421850f..c75980116 100644
--- a/src/js/storage.js
+++ b/src/js/storage.js
@@ -527,15 +527,27 @@
             return;
         }
 
+        // Only the lists referenced by the switches are touched.
+
         var filterLists = µb.remoteBlacklists;
+        var entry, state, location;
         var i = switches.length;
         while ( i-- ) {
-            if ( filterLists.hasOwnProperty(switches[i].location) === false ) {
+            entry = switches[i];
+            state = entry.off === true;
+            location = entry.location;
+            if ( filterLists.hasOwnProperty(location) === false ) {
+                if ( state !== true ) {
+                    filterLists[location] = { off: state };
+                }
                 continue;
             }
-            filterLists[switches[i].location].off = !!switches[i].off;
+            if ( filterLists[location].off === state ) {
+                continue;
+            }
+            filterLists[location].off = state;
         }
-        // Save switch states
+
         vAPI.storage.set({ 'remoteBlacklists': filterLists }, onFilterListsReady);
     };
 
@@ -564,9 +576,8 @@
             µb.purgeCompiledFilterList(path);
         }
         // Purge obsolete PSL
-        if ( metadata.hasOwnProperty(µb.pslPath) === false ) {
-            entry = metadata[µb.pslPath];
-            if ( entry.repoObsolete === true ) {
+        if ( metadata.hasOwnProperty(µb.pslPath) ) {
+            if ( metadata[µb.pslPath].repoObsolete === true ) {
                 µb.assets.purge('cache://compiled-publicsuffixlist');
             }
         }