diff --git a/.jshintrc b/.jshintrc
index f6a65273be..e61fe4778e 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -2,6 +2,7 @@
   "esnext": true,
   "indent": 2,
   "freeze": true,
+  "validthis": true,
   "camelcase": true,
   "unused": true,
   "eqnull": true,
diff --git a/lib/6to5/transformation/file.js b/lib/6to5/transformation/file.js
index e93a3bd07d..8ee4b9d312 100644
--- a/lib/6to5/transformation/file.js
+++ b/lib/6to5/transformation/file.js
@@ -348,8 +348,6 @@ File.prototype.parse = function (code) {
 };
 
 File.prototype.transform = function (ast) {
-  var self = this;
-
   this.debug();
 
   this.ast = ast;
diff --git a/lib/6to5/transformation/helpers/remap-async-to-generator.js b/lib/6to5/transformation/helpers/remap-async-to-generator.js
index 1161832439..fd5aacac31 100644
--- a/lib/6to5/transformation/helpers/remap-async-to-generator.js
+++ b/lib/6to5/transformation/helpers/remap-async-to-generator.js
@@ -3,7 +3,7 @@
 var t = require("../../types");
 
 var visitor = {
-  enter: function (node, parent, scope) {
+  enter: function (node) {
     if (t.isFunction(node)) this.skip();
 
     if (t.isAwaitExpression(node)) {
diff --git a/lib/6to5/transformation/transformer-pass.js b/lib/6to5/transformation/transformer-pass.js
index 9b16df92f2..a4a030bfc2 100644
--- a/lib/6to5/transformation/transformer-pass.js
+++ b/lib/6to5/transformation/transformer-pass.js
@@ -1,6 +1,5 @@
 module.exports = TransformerPass;
 
-var util     = require("../util");
 var contains = require("lodash/collection/contains");
 
 /**
diff --git a/lib/6to5/transformation/transformers/minification/dead-code-elimination.js b/lib/6to5/transformation/transformers/minification/dead-code-elimination.js
index b5ded93996..eb94292989 100644
--- a/lib/6to5/transformation/transformers/minification/dead-code-elimination.js
+++ b/lib/6to5/transformation/transformers/minification/dead-code-elimination.js
@@ -2,7 +2,7 @@ var t = require("../../../types");
 
 exports.optional = true;
 
-exports.ExpressionStatement = function (node, parent, scope) {
+exports.ExpressionStatement = function (node) {
   // remove consequenceless expressions such as local variables and literals
   //
   //   var foo = true; foo; -> var foo = true;
@@ -16,7 +16,7 @@ exports.ExpressionStatement = function (node, parent, scope) {
 };
 
 exports.IfStatement = {
-  exit: function (node, parent, scope) {
+  exit: function (node) {
     // todo: in scenarios where we can just return the consequent or
     // alternate we should drop the block statement if it contains no
     // block scoped variables
diff --git a/lib/6to5/transformation/transformers/minification/remove-console-calls.js b/lib/6to5/transformation/transformers/minification/remove-console-calls.js
index bac1650af9..afdb72f233 100644
--- a/lib/6to5/transformation/transformers/minification/remove-console-calls.js
+++ b/lib/6to5/transformation/transformers/minification/remove-console-calls.js
@@ -6,7 +6,7 @@ var isConsole = t.buildMatchMemberExpression("console", true);
 
 exports.optional = true;
 
-exports.CallExpression = function (node, parent, scope) {
+exports.CallExpression = function (node) {
   if (isConsole(node.callee)) {
     this.remove();
   }
diff --git a/lib/6to5/transformation/transformers/minification/remove-debugger.js b/lib/6to5/transformation/transformers/minification/remove-debugger.js
index b8950c888a..ae2eca0b0a 100644
--- a/lib/6to5/transformation/transformers/minification/remove-debugger.js
+++ b/lib/6to5/transformation/transformers/minification/remove-debugger.js
@@ -2,7 +2,7 @@ var t = require("../../../types");
 
 exports.optional = true;
 
-exports.ExpressionStatement = function (node, parent, scope) {
+exports.ExpressionStatement = function (node) {
   if (t.isIdentifier(node.expression, { name: "debugger" })) {
     this.remove();
   }
diff --git a/lib/6to5/transformation/transformers/minification/rename-local-variables.js b/lib/6to5/transformation/transformers/minification/rename-local-variables.js
index 56a8a43699..946de0c386 100644
--- a/lib/6to5/transformation/transformers/minification/rename-local-variables.js
+++ b/lib/6to5/transformation/transformers/minification/rename-local-variables.js
@@ -5,6 +5,7 @@ exports.optional = true;
 exports.Scope = function () {
   // todo: get all binding identifiers, generate compact names
   // that wont collide and then call the remap identifier helper
+
   // this transformer **has** to be ran last as it will absolutley
   // destroy the scope tree
 };
diff --git a/lib/6to5/transformation/transformers/other/self-contained.js b/lib/6to5/transformation/transformers/other/self-contained.js
index 5cfb06f95c..d97b4063ad 100644
--- a/lib/6to5/transformation/transformers/other/self-contained.js
+++ b/lib/6to5/transformation/transformers/other/self-contained.js
@@ -68,7 +68,7 @@ exports.post = function (file) {
   file.scope.traverse(file.ast, astVisitor, file);
 };
 
-exports.pre = function ( file) {
+exports.pre = function (file) {
   file.setDynamic("runtimeIdentifier", function () {
     return file.addImport("6to5-runtime/helpers", "to5Helpers");
   });
diff --git a/lib/6to5/transformation/transformers/other/use-strict.js b/lib/6to5/transformation/transformers/other/use-strict.js
index 3a7db8257e..fa5462911b 100644
--- a/lib/6to5/transformation/transformers/other/use-strict.js
+++ b/lib/6to5/transformation/transformers/other/use-strict.js
@@ -11,7 +11,7 @@ exports.post = function (file) {
 };
 
 exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, scope) {
+exports.FunctionExpression = function () {
   this.skip();
 };