diff --git a/src/renderers/shared/fiber/ReactFiber.js b/src/renderers/shared/fiber/ReactFiber.js
index d7ecf743711..6432ec33b44 100644
--- a/src/renderers/shared/fiber/ReactFiber.js
+++ b/src/renderers/shared/fiber/ReactFiber.js
@@ -223,8 +223,12 @@ var createFiber = function(tag : TypeOfWork, key : null | string) : Fiber {
     fiber._debugID = debugCounter++;
     fiber._debugSource = null;
     fiber._debugOwner = null;
+    if (typeof Object.preventExtensions === 'function') {
+      Object.preventExtensions(fiber);
+    }
   }
 
+
   return fiber;
 };