diff --git a/build.js b/build.js
index 90345d63d..1ef5555bd 100755
--- a/build.js
+++ b/build.js
@@ -1122,6 +1122,7 @@
     source = removeVar(source, 'reNative');
   }
   if (isRemoved(source, 'createIterator', 'clone', 'merge')) {
+    source = removeIsPlainObjectFallback(source);
     source = source.replace(/(?:\n +\/\*[^*]*\*+(?:[^\/][^*]*\*+)*\/)?\n *var iteratesOwnLast;|.+?iteratesOwnLast *=.+/g, '');
   }
   if (isRemoved(source, 'createIterator', 'isEqual')) {