diff --git a/Resources.php b/Resources.php
index bcab4bde..d3ef436a 100644
--- a/Resources.php
+++ b/Resources.php
@@ -117,6 +117,10 @@ $wgResourceModules['ext.uls.interface'] = array(
 	'position' => 'top',
 ) + $resourcePaths;
 
+// Anonymous users need 'jquery.jStorage' module for client side preference persistence.
+$wgResourceModules['ext.uls.interface.anon'] = $wgResourceModules['ext.uls.interface'];
+$wgResourceModules['ext.uls.interface.anon']['dependencies'][] = 'jquery.jStorage';
+
 $wgResourceModules['ext.uls.languagesettings'] = array(
 	'scripts' => 'resources/js/ext.uls.languagesettings.js',
 	'styles' => 'resources/css/ext.uls.languagesettings.css',
@@ -134,7 +138,10 @@ $wgResourceModules['ext.uls.preferences'] = array(
 	'dependencies' => array(
 		'mediawiki.user',
 		'mediawiki.api',
-		'jquery.jStorage',
+		'jquery.json',
+		// This is quite a big module and only needed for anons.
+		// Loaded conditionally in ext.uls.interface(.anon).
+		//'jquery.jStorage',
 	),
 ) + $resourcePaths;
 
diff --git a/UniversalLanguageSelector.hooks.php b/UniversalLanguageSelector.hooks.php
index 8de93f25..fecb441e 100644
--- a/UniversalLanguageSelector.hooks.php
+++ b/UniversalLanguageSelector.hooks.php
@@ -67,7 +67,11 @@ class UniversalLanguageSelectorHooks {
 
 		if ( self::isToolbarEnabled( $out->getUser() ) ) {
 			// Enable UI language selection for the user.
-			$out->addModules( 'ext.uls.interface' );
+			if (  $out->getUser()->isAnon() ) {
+				$out->addModules( 'ext.uls.interface.anon' );
+			} else {
+				$out->addModules( 'ext.uls.interface' );
+			}
 		}
 
 		return true;
diff --git a/resources/js/ext.uls.preferences.js b/resources/js/ext.uls.preferences.js
index f0cbb5fa..5edde741 100644
--- a/resources/js/ext.uls.preferences.js
+++ b/resources/js/ext.uls.preferences.js
@@ -115,13 +115,14 @@
 		 * Initialize
 		 */
 		init: function () {
+			var options;
+
 			if ( this.isAnon ) {
-				this.preferences = $.jStorage.get( this.preferenceName );
+				this.preferences = $.jStorage.get( this.preferenceName ) || {};
 			} else {
-				var options = mw.user.options.get( this.preferenceName );
-				this.preferences = $.parseJSON( options );
+				options = mw.user.options.get( this.preferenceName );
+				this.preferences = $.parseJSON( options ) || {};
 			}
-			this.preferences = this.preferences || {};
 		},
 
 		/**
@@ -157,7 +158,6 @@
 				$.jStorage.set( this.preferenceName, this.preferences );
 				callback.call( this, true );
 			} else {
-
 				// Logged in user. Use MW APIs to change preferences
 				saveOptionsWithToken( {
 					action: 'options',