diff --git a/server/utils.js b/server/utils.js
index e4d1f8ff..d2520386 100644
--- a/server/utils.js
+++ b/server/utils.js
@@ -48,7 +48,9 @@ export function addCorsSupport (req, res) {
   res.setHeader('Access-Control-Allow-Origin', req.headers.origin)
   res.setHeader('Access-Control-Allow-Methods', 'OPTIONS, GET')
   // Based on https://github.com/primus/access-control/blob/4cf1bc0e54b086c91e6aa44fb14966fa5ef7549c/index.js#L158
-  res.setHeader('Access-Control-Allow-Headers', req.headers['access-control-request-headers'])
+  if (req.headers['access-control-request-headers']) {
+    res.setHeader('Access-Control-Allow-Headers', req.headers['access-control-request-headers'])
+  }
 
   if (req.method === 'OPTIONS') {
     res.writeHead(200)