diff --git a/.jshintignore b/.jshintignore
index f05b1f265d..a4a39dfacb 100644
--- a/.jshintignore
+++ b/.jshintignore
@@ -1,2 +1,3 @@
 node_modules
 test
+lib/6to5/templates
diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index 79e9dcb3ff..15056b4ef5 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -15,8 +15,10 @@ var transform = module.exports = function (code, opts) {
     format:    {}
   });
 
+  var tree;
+
   try {
-    var tree = util.parse(code);
+    tree = util.parse(code);
   } catch (err) {
     err.message = opts.filename + ": " + err.message;
     throw err;
diff --git a/lib/6to5/transformers/block-binding.js b/lib/6to5/transformers/block-binding.js
index fa894dc256..84c33e8690 100644
--- a/lib/6to5/transformers/block-binding.js
+++ b/lib/6to5/transformers/block-binding.js
@@ -1,7 +1,6 @@
-var transform = require("../transform");
-var traverse  = require("../traverse");
-var util      = require("../util");
-var _         = require("lodash");
+var traverse = require("../traverse");
+var util     = require("../util");
+var _        = require("lodash");
 
 var isLet = function (node) {
   if (node.type === "VariableDeclaration" && node.kind === "let") {
diff --git a/lib/6to5/transformers/classes.js b/lib/6to5/transformers/classes.js
index 1e5a4c374c..502b9859d1 100644
--- a/lib/6to5/transformers/classes.js
+++ b/lib/6to5/transformers/classes.js
@@ -2,7 +2,7 @@ var traverse = require("../traverse");
 var util     = require("../util");
 var _        = require("lodash");
 
-exports.ClassDeclaration = function (node, parent, opts) {
+exports.ClassDeclaration = function (node) {
   var superName = node.superClass;
   var className = node.id;
 
@@ -91,9 +91,8 @@ var replaceInstanceSuperReferences = function (superName, method) {
     } else if (node.type === "MemberExpression") {
       // no accessing of super properties
 
-      var obj = node.object;
 
-      if (parent.object === node && obj.type === "Identifier" && obj.name === "super") {
+      if (isAccessingSuperProperties(parent, node)) {
         throw new Error("cannot access super properties");
       } else {
         return;
@@ -117,6 +116,12 @@ var replaceInstanceSuperReferences = function (superName, method) {
   });
 };
 
+var isAccessingSuperProperties = function (parent, node) {
+  var obj = node.object;
+  return obj.type === "Identifier" && obj.name === "super" &&
+         parent.object === node;
+};
+
 var addConstructor = function (construct, method) {
   construct.defaults = method.defaults;
   construct.params   = method.params;
diff --git a/lib/6to5/transformers/rest-parameters.js b/lib/6to5/transformers/rest-parameters.js
index 71e15918b1..ee229e3d6c 100644
--- a/lib/6to5/transformers/rest-parameters.js
+++ b/lib/6to5/transformers/rest-parameters.js
@@ -1,6 +1,6 @@
 var util = require("../util");
 
-exports.FunctionExpression = function (node, parent) {
+exports.FunctionExpression = function (node) {
   if (!node.rest) return;
 
   var rest = node.rest;
diff --git a/lib/6to5/transformers/spread.js b/lib/6to5/transformers/spread.js
index 7ac9ec69bf..dea623d8a1 100644
--- a/lib/6to5/transformers/spread.js
+++ b/lib/6to5/transformers/spread.js
@@ -1,7 +1,7 @@
 var util = require("../util");
 var _    = require("lodash");
 
-exports.ArrayExpression = function (node, parent) {
+exports.ArrayExpression = function (node) {
   //if (node.ignoreSpread) return;
 
   var elements = node.elements;
@@ -22,7 +22,7 @@ exports.ArrayExpression = function (node, parent) {
   return concat;
 };
 
-exports.CallExpression = function (node, parent) {
+exports.CallExpression = function (node) {
   var args = node.arguments;
 
   if (args.length && _.last(args).type === "SpreadElement") {
diff --git a/lib/6to5/util.js b/lib/6to5/util.js
index 501c220540..93d1337f90 100644
--- a/lib/6to5/util.js
+++ b/lib/6to5/util.js
@@ -29,7 +29,8 @@ exports.parse = function (code, opts) {
     return tree;
   } catch (err) {
     if (err.lineNumber) {
-      err.message = err.message + exports.codeFrame(code, err.lineNumber, err.column);
+      var frame = exports.codeFrame(code, err.lineNumber, err.column);
+      err.message = err.message + frame;
     }
     throw err;
   }
@@ -163,7 +164,7 @@ exports.codeFrame = function (lines, lineNumber, colNumber) {
 
 exports.repeat = function (width, cha) {
   cha = cha || " ";
-  return Array(width + 1).join(cha);
+  return new Array(width + 1).join(cha);
 };
 
 var templatesCacheLoc = __dirname + "/../../templates.json";