diff --git a/lib/mixins/property-effects.js b/lib/mixins/property-effects.js
index 7ec3331fbd..7e3300d918 100644
--- a/lib/mixins/property-effects.js
+++ b/lib/mixins/property-effects.js
@@ -1362,6 +1362,8 @@ export const PropertyEffects = dedupingMixin(superClass => {
       this.__readOnly;
       /** @type {!TemplateInfo} */
       this.__templateInfo;
+      /** @type {boolean} */
+      this._overrideLegacyUndefined;
     }
 
     get PROPERTY_EFFECT_TYPES() {