diff --git a/build.js b/build.js
index 6a4751cf1..7ea8d9468 100755
--- a/build.js
+++ b/build.js
@@ -1228,9 +1228,13 @@
    */
   function removeSupportNonEnumShadows(source) {
     source = removeSupportProp(source, 'nonEnumShadows');
+    source = removeVar(source, 'nonEnumProps');
     source = removeVar(source, 'shadowedProps');
     source = removeFromCreateIterator(source, 'shadowedProps');
 
+    // remove nested `nonEnumProps` assignments
+    source = source.replace(/^ *\(function[\s\S]+?\n *var length\b[\s\S]+?shadowedProps[\s\S]+?}\(\)\);\n/m, '');
+
     // remove `support.nonEnumShadows` from `iteratorTemplate`
     source = source.replace(getIteratorTemplate(source), function(match) {
       return match.replace(/(?: *\/\/.*\n)* *["']( *)<% *if *\(support\.nonEnumShadows[\s\S]+?["']\1<% *} *%>.+/, '');
@@ -1382,7 +1386,7 @@
    */
   function removeVar(source, varName) {
     // simplify complex variable assignments
-    if (/^(?:cloneableClasses|contextProps|ctorByClass|shadowedProps|whitespace)$/.test(varName)) {
+    if (/^(?:cloneableClasses|contextProps|ctorByClass|nonEnumProps|shadowedProps|whitespace)$/.test(varName)) {
       source = source.replace(RegExp('(var ' + varName + ' *=)[\\s\\S]+?;\\n\\n'), '$1=null;\n\n');
     }