diff --git a/bin/6to5-node b/bin/6to5-node
index 4853e710ca..e862736934 100755
--- a/bin/6to5-node
+++ b/bin/6to5-node
@@ -20,11 +20,15 @@ commander.parse(process.argv);
 
 to5.register();
 
+var _eval = function (code, filename) {
+  var mod = new Module(".");
+  return mod._compile(code, filename);
+};
+
 if (commander.eval) {
   var code = to5.transform(commander.eval, { filename: "eval" });
 
-  var mod = new Module(".");
-  var result = mod._compile(code, "eval");
+  var result = _eval(code, "eval");
   if (commander.print) console.log(result);
 } else {
   var filenames = commander.args;
@@ -43,7 +47,8 @@ function replStart() {
     prompt: "> ",
     input: process.stdin,
     output: process.stdout,
-    eval: replEval
+    eval: replEval,
+    useGlobal: true
   });
 }
 
@@ -55,7 +60,7 @@ function replEval(code, context, filename, callback) {
     code = code.slice(1, -2); // remove "(" and "\n)"
     code = to5.transform(code, { filename: filename });
 
-    result = vm.runInContext(code, context, filename, { displayErrors: false });
+    result = vm.runInThisContext(code, filename);
   } catch (e) {
     err = e;
   }
diff --git a/lib/6to5/register.js b/lib/6to5/register.js
index f2e1a54dd9..0d072cb2be 100644
--- a/lib/6to5/register.js
+++ b/lib/6to5/register.js
@@ -1,16 +1,23 @@
 require("./polyfill");
 
 var maps = {};
+var node = require("./node");
 var old  = require.extensions[".js"];
 
+// escodegen lazy requires source-map so we force it to load before we override
+// the built-in requires
+var escodegen = require("escodegen");
+escodegen.generate({ type: "Program", body: [] }, { sourceMap: true });
+
 // TODO: source maps - Error.prepareStackTrace override
 
-require.extensions[".js"] = function (m, filename) {
+require.extensions[".js"] =
+require.extensions[".es6"] = function (m, filename) {
   if (filename.indexOf("node_modules") >= 0) {
     return old.apply(this, arguments);
   }
 
-  var result = exports.transformFileSync(filename, {
+  var result = node.transformFileSync(filename, {
     sourceMapObject: true
   });
 
diff --git a/lib/6to5/transformers/constants.js b/lib/6to5/transformers/constants.js
index 65d579444b..0d1801b56c 100644
--- a/lib/6to5/transformers/constants.js
+++ b/lib/6to5/transformers/constants.js
@@ -16,7 +16,7 @@ exports.ForStatement = function (node) {
   };
 
   _.each(node.body, function (child) {
-    if (child.type === "VariableDeclaration" && child.kind === "const") {
+    if (child && child.type === "VariableDeclaration" && child.kind === "const") {
       _.each(child.declarations, function (declar) {
         var name = declar.id.name;
         check(declar, name);