diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index bd24298afe..3f3e813b5a 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -105,9 +105,9 @@ File.prototype.runTransformer = function (name, transformer) {
 
       if (!fns) return;
 
-      var fn = fns.enter || fns;
+      var fn = fns.enter;
       if (exit) fn = fns.exit;
-      if (!fn || !_.isFunction(fn)) return;
+      if (!fn) return;
 
       return fn(node, parent, self);
     };
diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index 2d5bfc4d60..0ebb89f1f3 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -86,3 +86,10 @@ transform.transformers = {
 
   _aliasFunctions:          require("./transformers/_alias-functions")
 };
+
+_.each(transform.transformers, function (transformer) {
+  _.each(transformer, function (fns, type) {
+    if (_.isFunction(fns)) fns = { enter: fns };
+    transformer[type] = fns;
+  });
+});