diff --git a/lib/_http_server.js b/lib/_http_server.js
index f77b8f6a7e7867..34e7b6d29c2cae 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -213,10 +213,8 @@ function writeHead(statusCode, reason, obj) {
         if (k) this.setHeader(k, obj[k]);
       }
     }
-    if (k === undefined) {
-      if (this._header) {
-        throw new errors.Error('ERR_HTTP_HEADERS_SENT');
-      }
+    if (k === undefined && this._header) {
+      throw new errors.Error('ERR_HTTP_HEADERS_SENT');
     }
     // only progressive api is used
     headers = this[outHeadersKey];