diff --git a/index.js b/index.js
index aed049d..971393b 100644
--- a/index.js
+++ b/index.js
@@ -247,8 +247,7 @@ function setCookie (res, name, val, options) {
 
   var prev = res.getHeader('set-cookie') || []
   var header = Array.isArray(prev) ? prev.concat(data)
-    : Array.isArray(data) ? [prev].concat(data)
-      : [prev, data]
+    : [prev, data]
 
   res.setHeader('set-cookie', header)
 }