diff --git a/lib/6to5/transformation/file.js b/lib/6to5/transformation/file.js
index db41639118..87d6775459 100644
--- a/lib/6to5/transformation/file.js
+++ b/lib/6to5/transformation/file.js
@@ -177,7 +177,7 @@ File.prototype.normalizeOptions = function (opts) {
   }
 
   var ensureEnabled = function (key) {
-    var namespace = transform.namespaces[key];
+    var namespace = transform.transformerNamespaces[key];
     if (namespace === "playground") opts.playground = true;
     if (namespace === "experimental") opts.experimental = true;
   };
diff --git a/lib/6to5/transformation/index.js b/lib/6to5/transformation/index.js
index 291ae19aa7..51c99fc225 100644
--- a/lib/6to5/transformation/index.js
+++ b/lib/6to5/transformation/index.js
@@ -56,8 +56,9 @@ transform._ensureTransformerNames = function (type, rawKeys) {
   return keys;
 };
 
-transform.transformers = object();
-transform.namespaces   = object();
+transform.transformerNamespaces = object();
+transform.transformers          = object();
+transform.namespaces            = object();
 
 transform.deprecatedTransformerMap = require("./transformers/deprecated");
 transform.moduleFormatters = require("./modules");
@@ -66,8 +67,10 @@ var rawTransformers = require("./transformers");
 
 each(rawTransformers, function (transformer, key) {
   var namespace = key.split(".")[0];
+
   transform.namespaces[namespace] = transform.namespaces[namespace] || [];
   transform.namespaces[namespace].push(key);
+  transform.transformerNamespaces[key] = namespace;
 
   transform.transformers[key] = new Transformer(key, transformer);
 });