diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index 518fddccb3..9420dfda58 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -13,8 +13,12 @@ var _         = require("lodash");
 
 function File(opts) {
   this.dynamicImports   = [];
+  this.dynamicImported  = [];
   this.dynamicImportIds = {};
+
+  this.dynamicData      = {};
   this.data             = {};
+
   this.opts             = File.normaliseOptions(opts);
   this.transformers     = this.getTransformers();
   this.ast              = {};
@@ -179,11 +183,23 @@ File.prototype.parseShebang = function (code) {
 };
 
 File.prototype.set = function (key, val) {
-  this.data[key] = val;
+  return this.data[key] = val;
+};
+
+File.prototype.setDynamic = function (key, fn) {
+  this.dynamicData[key] = fn;
 };
 
 File.prototype.get = function (key) {
-  return this.data[key];
+  var data = this.data[key];
+  if (data) {
+    return data;
+  } else {
+    var dynamic = this.dynamicData[key];
+    if (dynamic) {
+      return this.set(key, dynamic());
+    }
+  }
 };
 
 File.prototype.addImport = function (source, name) {
@@ -196,7 +212,9 @@ File.prototype.addImport = function (source, name) {
     var specifiers = [t.importSpecifier(t.identifier("default"), id)];
     var declar = t.importDeclaration(specifiers, t.literal(source));
     declar._blockHoist = 3;
-    this.dynamicImports.push(declar);
+    this.dynamicImported.push(declar);
+
+    this.moduleFormatter.importSpecifier(specifiers[0], declar, this.dynamicImports);
   }
 
   return id;