diff --git a/lib/mixins/properties-changed.js b/lib/mixins/properties-changed.js
index 9e481d673..ea06942a4 100644
--- a/lib/mixins/properties-changed.js
+++ b/lib/mixins/properties-changed.js
@@ -550,7 +550,9 @@ export const PropertiesChanged = dedupingMixin(
     _serializeValue(value) {
       switch (typeof value) {
         case 'boolean':
-          return value ? '' : undefined;
+          return value ?
+              (window.trustedTypes ? window.trustedTypes.emptyScript : '') :
+              undefined;
         default:
           return value != null ? value.toString() : undefined;
       }