diff --git a/lib/_http_incoming.js b/lib/_http_incoming.js
index 3ec23616b15b02..56ff31af8b17c1 100644
--- a/lib/_http_incoming.js
+++ b/lib/_http_incoming.js
@@ -110,7 +110,7 @@ IncomingMessage.prototype.destroy = function destroy(error) {
 IncomingMessage.prototype._addHeaderLines = _addHeaderLines;
 function _addHeaderLines(headers, n) {
   if (headers && headers.length) {
-    var dest;
+    let dest;
     if (this.complete) {
       this.rawTrailers = headers;
       dest = this.trailers;
@@ -119,7 +119,7 @@ function _addHeaderLines(headers, n) {
       dest = this.headers;
     }
 
-    for (var i = 0; i < n; i += 2) {
+    for (let i = 0; i < n; i += 2) {
       this._addHeaderLine(headers[i], headers[i + 1], dest);
     }
   }