diff --git a/lib/chai/core/assertions.js b/lib/chai/core/assertions.js
index b9189b8..53cfd51 100644
--- a/lib/chai/core/assertions.js
+++ b/lib/chai/core/assertions.js
@@ -1720,7 +1720,7 @@ module.exports = function (chai, _) {
     var obj = flag(this, 'object');
 
     this.assert(
-      Object.isSealed(obj)
+      Object.isFrozen(obj)
       , 'expected #{this} to be frozen'
       , 'expected #{this} to not be frozen'
     );