diff --git a/lib/index.js b/lib/index.js
index 5e52e86..a8ba980 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -9,10 +9,10 @@ function css(_) {
 
 function StyledVue(Vue) {
   Vue.component('styled-vue-global-css', {
-    render(h) {
-      const globalStyle = this.$parent.$options.globalStyle(this.$parent)
-      let css = ''
-      for (const key in globalStyle) {
+    render: function(h) {
+      var globalStyle = this.$parent.$options.globalStyle(this.$parent)
+      var css = ''
+      for (var key in globalStyle) {
         css += key + ':' + globalStyle[key] + ';'
       }
       return h('style', {}, [':root {' + css + '}'])