diff --git a/lib/6to5/generation/buffer.js b/lib/6to5/generation/buffer.js
index f881c8f533..6d731a17f0 100644
--- a/lib/6to5/generation/buffer.js
+++ b/lib/6to5/generation/buffer.js
@@ -2,10 +2,10 @@
 
 module.exports = Buffer;
 
-var util      = require("../util");
-var isNumber  = require("lodash/lang/isNumber");
 var isBoolean = require("lodash/lang/isBoolean");
 var contains  = require("lodash/collection/contains");
+var isNumber  = require("lodash/lang/isNumber");
+var util      = require("../util");
 
 function Buffer(position, format) {
   this.position = position;
diff --git a/lib/6to5/generation/index.js b/lib/6to5/generation/index.js
index 3c284bf009..c9ea55b912 100644
--- a/lib/6to5/generation/index.js
+++ b/lib/6to5/generation/index.js
@@ -12,12 +12,12 @@ var Whitespace   = require("./whitespace");
 var SourceMap    = require("./source-map");
 var Position     = require("./position");
 var Buffer       = require("./buffer");
+var extend       = require("lodash/object/extend");
+var merge        = require("lodash/object/merge");
+var each         = require("lodash/collection/each");
 var util         = require("../util");
 var n            = require("./node");
 var t            = require("../types");
-var each         = require("lodash/collection/each");
-var extend       = require("lodash/object/extend");
-var merge        = require("lodash/object/merge");
 
 function CodeGenerator(ast, opts, code) {
   opts = opts || {};
@@ -25,6 +25,7 @@ function CodeGenerator(ast, opts, code) {
   this.comments = ast.comments || [];
   this.tokens   = ast.tokens || [];
   this.format   = CodeGenerator.normalizeOptions(code, opts);
+  this.opts     = opts;
   this.ast      = ast;
 
   this.whitespace = new Whitespace(this.tokens, this.comments);
diff --git a/lib/6to5/transformation/helpers/define-map.js b/lib/6to5/transformation/helpers/define-map.js
index cd7f82b0f1..abbd846fda 100644
--- a/lib/6to5/transformation/helpers/define-map.js
+++ b/lib/6to5/transformation/helpers/define-map.js
@@ -1,6 +1,6 @@
 var cloneDeep = require("lodash/lang/cloneDeep");
 var traverse  = require("../../traversal");
-var clone      = require("lodash/lang/clone");
+var clone     = require("lodash/lang/clone");
 var each      = require("lodash/collection/each");
 var has       = require("lodash/object/has");
 var t         = require("../../types");
diff --git a/lib/6to5/transformation/modules/amd.js b/lib/6to5/transformation/modules/amd.js
index eca421f199..4ee4b44268 100644
--- a/lib/6to5/transformation/modules/amd.js
+++ b/lib/6to5/transformation/modules/amd.js
@@ -29,9 +29,8 @@ AMDFormatter.prototype.buildDependencyLiterals = function () {
  * Wrap the entire body in a `define` wrapper.
  */
 
-AMDFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-  var body    = program.body;
+AMDFormatter.prototype.transform = function (program) {
+  var body = program.body;
 
   // build an array of module names
 
diff --git a/lib/6to5/transformation/modules/system.js b/lib/6to5/transformation/modules/system.js
index 555023c7e9..4f0f3f0208 100644
--- a/lib/6to5/transformation/modules/system.js
+++ b/lib/6to5/transformation/modules/system.js
@@ -158,9 +158,7 @@ var hoistFunctionsVisitor = {
   }
 };
 
-SystemFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-
+SystemFormatter.prototype.transform = function (program) {
   var hoistDeclarators = [];
   var moduleName = this.getModuleName();
   var moduleNameLiteral = t.literal(moduleName);
diff --git a/lib/6to5/transformation/modules/umd.js b/lib/6to5/transformation/modules/umd.js
index da86b4dfb5..a4bdf92ec1 100644
--- a/lib/6to5/transformation/modules/umd.js
+++ b/lib/6to5/transformation/modules/umd.js
@@ -13,9 +13,8 @@ function UMDFormatter() {
 
 util.inherits(UMDFormatter, AMDFormatter);
 
-UMDFormatter.prototype.transform = function (ast) {
-  var program = ast.program;
-  var body    = program.body;
+UMDFormatter.prototype.transform = function (program) {
+  var body = program.body;
 
   // build an array of module names
 
diff --git a/lib/6to5/transformation/transformers/internal/module-formatter.js b/lib/6to5/transformation/transformers/internal/module-formatter.js
index f1a7c81c89..3bacf0a1dd 100644
--- a/lib/6to5/transformation/transformers/internal/module-formatter.js
+++ b/lib/6to5/transformation/transformers/internal/module-formatter.js
@@ -2,16 +2,16 @@
 
 var useStrict = require("../../helpers/use-strict");
 
-exports.ast = {
-  exit: function (ast, file) {
+exports.Program = {
+  exit: function (program, parent, scope, context, file) {
     if (!file.transformers["es6.modules"].canRun()) return;
 
-    useStrict.wrap(ast.program, function () {
-      ast.program.body = file.dynamicImports.concat(ast.program.body);
+    useStrict.wrap(program, function () {
+      program.body = file.dynamicImports.concat(program.body);
     });
 
     if (file.moduleFormatter.transform) {
-      file.moduleFormatter.transform(ast);
+      file.moduleFormatter.transform(program);
     }
   }
 };
diff --git a/lib/6to5/transformation/transformers/other/regenerator.js b/lib/6to5/transformation/transformers/other/regenerator.js
index d4a9119e7a..766956e95d 100644
--- a/lib/6to5/transformation/transformers/other/regenerator.js
+++ b/lib/6to5/transformation/transformers/other/regenerator.js
@@ -1,16 +1,14 @@
 "use strict";
 
 var regenerator = require("regenerator-6to5");
-var t           = require("../../../types");
 
 exports.check = function (node) {
   return t.isFunction(node) && (node.async || node.generator);
 };
 
-exports.ast = {
-  before: function (ast, file) {
-    regenerator.transform(ast, {
-      includeRuntime: file.opts.includeRegenerator && "if used"
-    });
+exports.Program = {
+  enter: function (ast) {
+    regenerator.transform(ast);
+    this.stop();
   }
 };
diff --git a/lib/6to5/transformation/transformers/other/self-contained.js b/lib/6to5/transformation/transformers/other/self-contained.js
index d1e7749138..3ff1c8d9da 100644
--- a/lib/6to5/transformation/transformers/other/self-contained.js
+++ b/lib/6to5/transformation/transformers/other/self-contained.js
@@ -64,8 +64,8 @@ exports.manipulateOptions = function (opts) {
   if (opts.whitelist.length) opts.whitelist.push("es6.modules");
 };
 
-exports.ast = {
-  enter: function (ast, file) {
+exports.Program = {
+  enter: function (node, parent, scope, context, file) {
     file.setDynamic("runtimeIdentifier", function () {
       return file.addImport("6to5-runtime/helpers", "to5Helpers");
     });
@@ -79,8 +79,8 @@ exports.ast = {
     });
   },
 
-  after: function (ast, file) {
-    file.scope.traverse(ast, astVisitor, file);
+  exit: function (node, parent, scope, context, file) {
+    file.scope.traverse(node, astVisitor, file);
   }
 };
 
diff --git a/lib/6to5/transformation/transformers/other/use-strict.js b/lib/6to5/transformation/transformers/other/use-strict.js
index 12751e4ba3..87d9672cc8 100644
--- a/lib/6to5/transformation/transformers/other/use-strict.js
+++ b/lib/6to5/transformation/transformers/other/use-strict.js
@@ -3,10 +3,10 @@
 var useStrict = require("../../helpers/use-strict");
 var t         = require("../../../types");
 
-exports.ast = {
-  exit: function (ast) {
-    if (!useStrict.has(ast.program)) {
-      ast.program.body.unshift(t.expressionStatement(t.literal("use strict")));
+exports.Program = {
+  exit: function (program) {
+    if (!useStrict.has(program)) {
+      program.body.unshift(t.expressionStatement(t.literal("use strict")));
     }
   }
 };