diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index d26194a1e3..24b3c7350d 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -39,6 +39,17 @@ File.normaliseOptions = function (opts) {
   // normalise windows path separators to unix
   opts.filename = opts.filename.replace(/\\/g, "/");
 
+  opts.blacklist = util.arrayify(opts.blacklist);
+  opts.whitelist = util.arrayify(opts.whitelist);
+
+  _.defaults(opts, {
+    moduleRoot: opts.sourceRoot
+  });
+
+  _.defaults(opts, {
+    sourceRoot: opts.moduleRoot
+  });
+
   _.defaults(opts, {
     filenameRelative: opts.filename
   });