diff --git a/lib/Layout.js b/lib/Layout.js
index <HASH>..<HASH> 100644
--- a/lib/Layout.js
+++ b/lib/Layout.js
@@ -482,7 +482,7 @@ function Sequence (elt_layout, count, property) {
     /** The number of elements in the sequence. */
     this.count = count;
 
-    Object.freeze();
+    Object.freeze(this);
 }
 Sequence.prototype = Object.create(Layout.prototype);
 Sequence.prototype.constructor = Sequence;
@@ -796,7 +796,7 @@ function VariantLayout (union,
      * VariantLayout#union|union}. */
     this.layout = layout;
 
-    Object.freeze();
+    Object.freeze(this);
 }
 VariantLayout.prototype = Object.create(Layout.prototype);
 VariantLayout.prototype.constructor = VariantLayout;
Layout: fix mis-application of Object.freeze

This was freezing the constructor which was not intended and is not
permitted in ES5.