diff --git a/lib/6to5/api/register/node.js b/lib/6to5/api/register/node.js
index f4837a4276..3c924627b5 100644
--- a/lib/6to5/api/register/node.js
+++ b/lib/6to5/api/register/node.js
@@ -44,8 +44,10 @@ var mtime = function (filename) {
 var compile = function (filename) {
   var result;
 
+  var cacheKey = filename + ":" + JSON.stringify(transformOpts);
+
   if (cache) {
-    var cached = cache[filename];
+    var cached = cache[cacheKey];
     if (cached && cached.mtime === mtime(filename)) {
       result = cached;
     }
@@ -60,7 +62,7 @@ var compile = function (filename) {
 
   if (cache) {
     result.mtime = mtime(filename);
-    cache[filename] = result;
+    cache[cacheKey] = result;
   }
 
   maps[filename] = result.map;