diff --git a/src/js/messaging.js b/src/js/messaging.js
index 0b541caf5..d6327e6a8 100644
--- a/src/js/messaging.js
+++ b/src/js/messaging.js
@@ -886,7 +886,7 @@ const backupUserData = async function() {
         version: vAPI.app.version,
         userSettings: µb.userSettings,
         selectedFilterLists: µb.selectedFilterLists,
-        hiddenSettings: µb.hiddenSettings,
+        hiddenSettings: µb.getModifiedHiddenSettings(),
         whitelist: µb.arrayFromWhitelist(µb.netWhitelist),
         // String representation eventually to be deprecated
         netWhitelist: µb.stringFromWhitelist(µb.netWhitelist),
@@ -927,12 +927,24 @@ const restoreUserData = async function(request) {
 
     // Restore user data
     vAPI.storage.set(userData.userSettings);
+
+    // Restore advanced settings.
     let hiddenSettings = userData.hiddenSettings;
     if ( hiddenSettings instanceof Object === false ) {
         hiddenSettings = µBlock.hiddenSettingsFromString(
             userData.hiddenSettingsString || ''
         );
     }
+    // Discard unknown setting or setting with default value.
+    for ( const key in hiddenSettings ) {
+        if (
+            this.hiddenSettingsDefault.hasOwnProperty(key) === false ||
+            hiddenSettings[key] === this.hiddenSettingsDefault[key]
+        ) {
+            delete hiddenSettings[key];
+        }
+    }
+
     // Whitelist directives can be represented as an array or as a
     // (eventually to be deprecated) string.
     let whitelist = userData.whitelist;
@@ -944,7 +956,7 @@ const restoreUserData = async function(request) {
         whitelist = userData.netWhitelist.split('\n');
     }
     vAPI.storage.set({
-        hiddenSettings: hiddenSettings,
+        hiddenSettings,
         netWhitelist: whitelist || [],
         dynamicFilteringString: userData.dynamicFilteringString || '',
         urlFilteringString: userData.urlFilteringString || '',
diff --git a/src/js/storage.js b/src/js/storage.js
index 75921f92d..79ea86051 100644
--- a/src/js/storage.js
+++ b/src/js/storage.js
@@ -119,17 +119,21 @@
 // This way the new default values in the future will properly apply for those
 // which were not modified by the user.
 
-µBlock.saveHiddenSettings = function() {
-    const bin = { hiddenSettings: {} };
+µBlock.getModifiedHiddenSettings = function() {
+    const out = {};
     for ( const prop in this.hiddenSettings ) {
         if (
             this.hiddenSettings.hasOwnProperty(prop) &&
             this.hiddenSettings[prop] !== this.hiddenSettingsDefault[prop]
         ) {
-            bin.hiddenSettings[prop] = this.hiddenSettings[prop];
+            out[prop] = this.hiddenSettings[prop];
         }
     }
-    vAPI.storage.set(bin);
+    return out;
+};
+
+µBlock.saveHiddenSettings = function() {
+    vAPI.storage.set({ hiddenSettings: this.getModifiedHiddenSettings() });
 };
 
 self.addEventListener('hiddenSettingsChanged', ( ) => {