diff --git a/lib/6to5/register.js b/lib/6to5/register.js
index f09ea6396d..840039b385 100644
--- a/lib/6to5/register.js
+++ b/lib/6to5/register.js
@@ -21,6 +21,7 @@ sourceMapSupport.install({
 //
 
 var ignoreRegex = /node_modules/;
+var blacklist   = [];
 var exts        = {};
 var maps        = {};
 var old         = require.extensions[".js"];
@@ -31,7 +32,8 @@ var loader = function (m, filename) {
   }
 
   var result = to5.transformFileSync(filename, {
-    sourceMap: true
+    sourceMap: true,
+    blacklist: blacklist
   });
 
   maps[filename] = result.map;
@@ -63,4 +65,6 @@ module.exports = function (opts) {
   }
 
   if (opts.extensions) hookExtensions(opts.extensions);
+
+  if (opts.blacklist) blacklist = opts.blacklist;
 };