diff --git a/lib/isomorphic/gatsby-helpers.js b/lib/isomorphic/gatsby-helpers.js
index 2a1b7516f8881..8a5c7dde5d12e 100644
--- a/lib/isomorphic/gatsby-helpers.js
+++ b/lib/isomorphic/gatsby-helpers.js
@@ -27,7 +27,7 @@ const prefixLink = (_link) => {
     if (isDataURL(_link)) {
       return _link
     } else {
-      if (!_link.startsWith('/')) {
+      if (_link.slice(0, 1) !== '/') {
         return `${config.linkPrefix}/${_link}`
       }
       return `${config.linkPrefix}${_link}`