diff --git a/.eslintrc b/.eslintrc
index 650e2795e6..cc8376fbf8 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -1,5 +1,5 @@
 {
-  "parser": "/Users/sebastian/Projects/6to5/6to5/eslint.js",
+  "parser": "/Users/sebastian/Projects/babel/core/eslint.js",
   "ecmaFeatures": {
     "blockBindings": true
   },
@@ -12,7 +12,12 @@
     "key-spacing": 0,
     "no-return-assign": 0,
     "consistent-return": 0,
-    "no-shadow": 0
+    "no-shadow": 0,
+    "no-comma-dangle": 0,
+    "no-use-before-define": 0,
+    "no-empty": 0,
+    "new-parens": 0,
+    "no-cond-assign": 0
   },
   "env": {
     "node": true
diff --git a/eslint.js b/eslint.js
index 3879e0cc05..010d937dfc 100644
--- a/eslint.js
+++ b/eslint.js
@@ -1,6 +1,9 @@
-var traverse = require("./lib/babel/traversal");
-var Module   = require("module");
-var acorn    = require("acorn-babel");
+var acornToEsprima = require("./lib/babel/helpers/acorn-to-esprima");
+var traverse       = require("./lib/babel/traversal");
+var extend         = require("lodash/object/extend");
+var Module         = require("module");
+var acorn          = require("acorn-babel");
+var t              = require("./lib/babel/types");
 
 var hasPatched = false;
 
@@ -8,27 +11,18 @@ function monkeypatch() {
   if (hasPatched) return;
   hasPatched = true;
 
-  var mod = new Module(require.resolve("eslint"));
-
   // monkeypatch estraverse
-  //var estraverse = mod.require("estraverse");
+  var estraverse = require("estraverse");
+  extend(estraverse.VisitorKeys, t.VISITOR_KEYS);
 
   // monkeypatch escope
-  var escope = mod.require("escope");
-  console.log(escope);
-}
-
-var tokTypes = acorn.tokTypes;
-
-function toEsprimaToken(token) {
-  var type = token.type;
-
-  if (type === tokTypes.name) {
-    token.type = "Identifier";
-  } else if (type === tokTypes.semi || type === tokTypes.comma || type === tokTypes.parenL || type === tokTypes.parenR || type === tokTypes.braceL || type === tokTypes.braceR) {
-    token.type = "Punctuator";
-    token.value = type.type;
-  }
+  var escope = require("eslint/node_modules/escope");
+  var analyze = escope.analyze;
+  escope.analyze = function (ast, opts) {
+    opts.sourceType = 'module';
+    opts.ecmaVersion = 6;
+    return analyze.call(this, ast, opts)
+  };
 }
 
 exports.parse = function (code) {
@@ -46,14 +40,13 @@ exports.parse = function (code) {
   var ast = acorn.parse(code, opts);
 
   // convert tokens
-  ast.tokens = tokens.map(function (token) {
-    return toEsprimaToken(token) || token;
-  });
+  ast.tokens = tokens.map(acornToEsprima.toEsprimaToken);
 
   // add comments
   ast.comments = comments;
 
   // transform esprima and acorn divergent nodes
+  acornToEsprima.toEsprimaAST(ast);
 
   return ast;
 };
diff --git a/package.json b/package.json
index d48f8987a2..89106c1426 100644
--- a/package.json
+++ b/package.json
@@ -70,6 +70,7 @@
     "babel": "4.5.1",
     "browserify": "^9.0.3",
     "chai": "^2.0.0",
+    "eslint": "^0.15.1",
     "esvalid": "^1.1.0",
     "istanbul": "^0.3.5",
     "matcha": "^0.6.0",
diff --git a/src/babel/api/browser.js b/src/babel/api/browser.js
index 715b0b471d..248d668e37 100644
--- a/src/babel/api/browser.js
+++ b/src/babel/api/browser.js
@@ -4,14 +4,12 @@ transform.version = require("../../../package").version;
 
 transform.transform = transform;
 
-transform.run = function (code, opts) {
-  opts ||= {};
+transform.run = function (code, opts = {}) {
   opts.sourceMap = "inline";
   return new Function(transform(code, opts).code)();
 };
 
-transform.load = function (url, callback, opts, hold) {
-  opts ||= {};
+transform.load = function (url, callback, opts = {}, hold) {
   opts.filename ||= url;
 
   var xhr = global.ActiveXObject ? new global.ActiveXObject("Microsoft.XMLHTTP") : new global.XMLHttpRequest();
diff --git a/src/babel/api/node.js b/src/babel/api/node.js
index 9811a81ec6..74aa437d6a 100644
--- a/src/babel/api/node.js
+++ b/src/babel/api/node.js
@@ -43,8 +43,7 @@ export function transformFile(filename, opts, callback) {
   });
 }
 
-export function transformFileSync(filename, opts) {
-  opts ||= {};
+export function transformFileSync(filename, opts = {}) {
   opts.filename = filename;
   return transform(fs.readFileSync(filename), opts);
 }
diff --git a/src/babel/api/register/node.js b/src/babel/api/register/node.js
index e4dde63928..e344ca0ab6 100644
--- a/src/babel/api/register/node.js
+++ b/src/babel/api/register/node.js
@@ -138,10 +138,7 @@ var hookExtensions = function (_exts) {
 
 hookExtensions(util.canCompile.EXTENSIONS);
 
-export default function (opts) {
-  // normalize options
-  opts ||= {};
-
+export default function (opts = {}) {
   if (opts.only != null) onlyRegex = util.regexify(opts.only);
   if (opts.ignore != null) ignoreRegex = util.regexify(opts.ignore);
 
diff --git a/src/babel/build-helpers.js b/src/babel/build-helpers.js
index 6e69dcd770..8793445ed3 100644
--- a/src/babel/build-helpers.js
+++ b/src/babel/build-helpers.js
@@ -5,7 +5,7 @@ import t from "./types";
 
 export default function (body, namespace, whitelist = []) {
   each(File.helpers, function (name) {
-    if (whitelist.length && whitelist.indexOf(name) == -1) return;
+    if (whitelist.length && whitelist.indexOf(name) === -1) return;
 
     var key = t.identifier(t.toIdentifier(name));
     body.push(t.expressionStatement(
diff --git a/src/babel/generation/index.js b/src/babel/generation/index.js
index 373bd8220d..a2cc4e2d95 100644
--- a/src/babel/generation/index.js
+++ b/src/babel/generation/index.js
@@ -11,9 +11,7 @@ import n from "./node";
 import t from "../types";
 
 class CodeGenerator {
-  constructor(ast, opts, code) {
-    opts ||= {};
-
+  constructor(ast, opts = {}, code) {
     this.comments = ast.comments || [];
     this.tokens   = ast.tokens || [];
     this.format   = CodeGenerator.normalizeOptions(code, opts);
@@ -91,8 +89,7 @@ class CodeGenerator {
       return this.print(node, parent, opts);
     };
 
-    print.sequence = (nodes, opts) => {
-      opts ||= {};
+    print.sequence = (nodes, opts = {}) => {
       opts.statement = true;
       return this.printJoin(print, nodes, opts);
     };
@@ -101,8 +98,7 @@ class CodeGenerator {
       return this.printJoin(print, nodes, opts);
     };
 
-    print.list = function (items, opts) {
-      opts ||= {};
+    print.list = function (items, opts = {}) {
       opts.separator ||= ", ";
       print.join(items, opts);
     };
@@ -118,7 +114,7 @@ class CodeGenerator {
     return print;
   }
 
-  print(node, parent, opts) {
+  print(node, parent, opts = {}) {
     if (!node) return "";
 
     if (parent && parent._compact) {
@@ -130,8 +126,6 @@ class CodeGenerator {
       this.format.concise = true;
     }
 
-    opts ||= {};
-
     var newline = (leading) => {
       if (!opts.statement && !n.isUserWhitespacable(node, parent)) {
         return;
@@ -197,11 +191,9 @@ class CodeGenerator {
     this.format.concise = oldConcise;
   }
 
-  printJoin(print, nodes, opts) {
+  printJoin(print, nodes, opts = {}) {
     if (!nodes || !nodes.length) return;
 
-    opts ||= {};
-
     var len = nodes.length;
 
     if (opts.indent) this.indent();
diff --git a/src/babel/generation/node/whitespace.js b/src/babel/generation/node/whitespace.js
index bf9dc32cf4..c4ae5e0bba 100644
--- a/src/babel/generation/node/whitespace.js
+++ b/src/babel/generation/node/whitespace.js
@@ -3,9 +3,7 @@ import each from "lodash/collection/each";
 import map from "lodash/collection/map";
 import t from "../../types";
 
-function crawl(node, state) {
-  state ||= {};
-
+function crawl(node, state = {}) {
   if (t.isMemberExpression(node)) {
     crawl(node.object, state);
     if (node.computed) crawl(node.property, state);
diff --git a/src/babel/helpers/acorn-to-esprima.js b/src/babel/helpers/acorn-to-esprima.js
new file mode 100644
index 0000000000..20d25999b2
--- /dev/null
+++ b/src/babel/helpers/acorn-to-esprima.js
@@ -0,0 +1,49 @@
+import traverse from "../traversal";
+import { tokTypes } from "acorn-babel";
+import t from "../types";
+
+export function toEsprimaToken(token) {
+  var type = token.type;
+
+  if (type === tokTypes.name) {
+    token.type = "Identifier";
+  } else if (type === tokTypes.semi || type === tokTypes.comma || type === tokTypes.parenL || type === tokTypes.parenR || type === tokTypes.braceL || type === tokTypes.braceR) {
+    token.type = "Punctuator";
+    token.value = type.type;
+  }
+
+  return token;
+}
+
+export function toEsprimaAST(ast) {
+  traverse(ast, astTransformVisitor);
+}
+
+var astTransformVisitor = {
+  noScope: true,
+  enter(node) {
+    if (t.isImportBatchSpecifier(node)) {
+      node.type = "ImportNamespaceSpecifier";
+      node.id = node.name;
+      delete node.name;
+    } else if (t.isFunction(node)) {
+      node.defaults = [];
+
+      node.params = node.params.map(function (param) {
+        if (t.isAssignmentPattern(param)) {
+          node.defaults.push(param.right);
+          return param.left;
+        } else {
+          node.defaults.push(null);
+          return param;
+        }
+      });
+
+      if (t.isRestElement(node.params[node.params.length - 1])) {
+        node.rest = node.params.pop();
+      }
+    } else if (t.isClassProperty(node)) {
+      this.remove();
+    }
+  }
+};
diff --git a/src/babel/transformation/file.js b/src/babel/transformation/file.js
index 84e8852b61..03503beaf4 100644
--- a/src/babel/transformation/file.js
+++ b/src/babel/transformation/file.js
@@ -369,9 +369,7 @@ export default class File {
     // todo, (node, msg)
   }
 
-  errorWithNode(node, msg, Error) {
-    Error ||= SyntaxError;
-
+  errorWithNode(node, msg, Error = SyntaxError) {
     var loc = node.loc.start;
     var err = new Error("Line " + loc.line + ": " + msg);
     err.loc = loc;
diff --git a/src/babel/transformation/helpers/name-method.js b/src/babel/transformation/helpers/name-method.js
index 105d851e42..eb197002c2 100644
--- a/src/babel/transformation/helpers/name-method.js
+++ b/src/babel/transformation/helpers/name-method.js
@@ -49,7 +49,7 @@ var visit = function (node, name, scope) {
     selfReference:  false,
     outerDeclar:    scope.getBindingIdentifier(name),
     references:     [],
-    name:           name,
+    name:           name
   };
 
   // check to see if we have a local binding of the id we're setting inside of
diff --git a/src/babel/transformation/helpers/replace-supers.js b/src/babel/transformation/helpers/replace-supers.js
index bf5de32370..3df9190db8 100644
--- a/src/babel/transformation/helpers/replace-supers.js
+++ b/src/babel/transformation/helpers/replace-supers.js
@@ -4,16 +4,16 @@ import * as messages from "../../messages";
 import t from "../../types";
 
 
-var isIllegalBareSuper = function (node, parent) {
+function isIllegalBareSuper(node, parent) {
   if (!isSuper(node, parent)) return false;
   if (t.isMemberExpression(parent, { computed: false })) return false;
   if (t.isCallExpression(parent, { callee: node })) return false;
   return true;
-};
+}
 
-var isSuper = function (node, parent) {
+function isSuper(node, parent) {
   return t.isIdentifier(node, { name: "super" }) && t.isReferenced(node, parent);
-};
+}
 
 var visitor = {
   enter(node, parent, scope, state) {
diff --git a/src/babel/transformation/transformers/es6/for-of.js b/src/babel/transformation/transformers/es6/for-of.js
index ff0ebcac3f..0dcaa053bb 100644
--- a/src/babel/transformation/transformers/es6/for-of.js
+++ b/src/babel/transformation/transformers/es6/for-of.js
@@ -141,7 +141,7 @@ var spec = function (node, parent, scope, file) {
 
   var iteratorKey = scope.generateUidIdentifier("iterator");
 
-  var node = util.template("for-of", {
+  var template = util.template("for-of", {
     ITERATOR_HAD_ERROR_KEY: scope.generateUidIdentifier("didIteratorError"),
     ITERATOR_COMPLETION:    scope.generateUidIdentifier("iteratorNormalCompletion"),
     ITERATOR_ERROR_KEY:     scope.generateUidIdentifier("iteratorError"),
@@ -151,16 +151,16 @@ var spec = function (node, parent, scope, file) {
     BODY:                   null
   });
 
-  var loop = node[3].block.body[0];
+  var loop = template[3].block.body[0];
 
   //
 
   scope.traverse(node, breakVisitor, {
     iteratorKey: iteratorKey,
+    label:       t.isLabeledStatement(parent) && parent.label.name,
     wrapReturn:  function (node) {
       return t.ifStatement(t.memberExpression(iteratorKey, t.identifier("return")), node);
-    },
-    label:       t.isLabeledStatement(parent) && parent.label.name
+    }
   });
 
   //
@@ -168,6 +168,6 @@ var spec = function (node, parent, scope, file) {
   return {
     declar: declar,
     loop:   loop,
-    node:   node
+    node:   template
   };
 };
diff --git a/src/babel/transformation/transformers/es7/comprehensions.js b/src/babel/transformation/transformers/es7/comprehensions.js
index 654c944af9..6ff0ba400e 100644
--- a/src/babel/transformation/transformers/es7/comprehensions.js
+++ b/src/babel/transformation/transformers/es7/comprehensions.js
@@ -11,7 +11,7 @@ export function ComprehensionExpression(node, parent, scope, file) {
   return callback(node, parent, scope, file);
 }
 
-var generator = function (node) {
+function generator(node) {
   var body = [];
   var container = t.functionExpression(null, [], t.blockStatement(body), true);
   container._aliasFunction = true;
@@ -21,9 +21,9 @@ var generator = function (node) {
   }));
 
   return t.callExpression(container, []);
-};
+}
 
-var array = function (node, parent, scope, file) {
+function array(node, parent, scope, file) {
   var uid = scope.generateUidBasedOnNode(parent, file);
 
   var container = util.template("array-comprehension-container", {
@@ -50,4 +50,4 @@ var array = function (node, parent, scope, file) {
   body.push(returnStatement);
 
   return container;
-};
+}