diff --git a/gatsby-config.js b/gatsby-config.js
index d4da98a..e872449 100644
--- a/gatsby-config.js
+++ b/gatsby-config.js
@@ -59,7 +59,8 @@ module.exports = {
         `,
         feeds: [{
           serialize: ({ query: { site, allMarkdownRemark } }) => (
-            allMarkdownRemark.edges.map((edge) => Object.assign({}, edge.node.frontmatter, {
+            allMarkdownRemark.edges.map((edge) => ({
+              ...edge.node.frontmatter,
               description: edge.node.frontmatter.description,
               date: edge.node.frontmatter.date,
               url: site.siteMetadata.site_url + edge.node.fields.slug,