diff --git a/lib/6to5/transformation/transformers/other/self-contained.js b/lib/6to5/transformation/transformers/other/self-contained.js
index 0c040b5ab0..d6d890038f 100644
--- a/lib/6to5/transformation/transformers/other/self-contained.js
+++ b/lib/6to5/transformation/transformers/other/self-contained.js
@@ -1,10 +1,12 @@
 "use strict";
 
+var includes = require("lodash/collection/includes");
 var util     = require("../../../util");
 var core     = require("core-js/library");
-var t        = require("../../../types");
 var has      = require("lodash/object/has");
-var includes = require("lodash/collection/includes");
+var t        = require("../../../types");
+
+var isSymboliterator = t.buildMatchMemberExpression("Symbol.iterator");
 
 var coreHas = function (node) {
   return node.name !== "_" && has(core, node.name);
@@ -47,8 +49,7 @@ var astVisitor = {
       if (!callee.computed) return false;
 
       prop = callee.property;
-      if (!t.isIdentifier(prop.object, { name: "Symbol" })) return false;
-      if (!t.isIdentifier(prop.property, { name: "iterator" })) return false;
+      if (!isSymboliterator(prop)) return false;
 
       return util.template("corejs-iterator", {
         CORE_ID: file.get("coreIdentifier"),
@@ -60,9 +61,7 @@ var astVisitor = {
       if (node.operator !== "in") return;
 
       var left = node.left;
-      if (!t.isMemberExpression(left)) return;
-      if (!t.isIdentifier(left.object, { name: "Symbol" })) return;
-      if (!t.isIdentifier(left.property, { name: "iterator" })) return;
+      if (!isSymboliterator(left)) return;
 
       return util.template("corejs-is-iterator", {
         CORE_ID: file.get("coreIdentifier"),