diff --git a/lib/legacy/class.js b/lib/legacy/class.js
index c6d70e536f..66288c4765 100644
--- a/lib/legacy/class.js
+++ b/lib/legacy/class.js
@@ -242,10 +242,10 @@ function GenerateClassFromInfo(info, Base, behaviors) {
     /** @override */
     _initializeProperties() {
       // Enable disable-upgrade use when `legacyOptimizations` setting is on.
-      if (legacyOptimizations && !this.hasAttribute(DISABLED_ATTR)) {
-        super._initializeProperties();
-      } else {
+      if (legacyOptimizations && this.hasAttribute(DISABLED_ATTR)) {
         this.__isUpgradeDisabled = true;
+      } else {
+        super._initializeProperties();
       }
     }