diff --git a/lib/url.js b/lib/url.js
index 6810229f1338d5..ff54988f424326 100644
--- a/lib/url.js
+++ b/lib/url.js
@@ -249,10 +249,11 @@ Url.prototype.parse = function parse(url, parseQueryString, slashesDenoteHost) {
     }
   }
 
-  var proto = protocolPattern.exec(rest);
+  let proto = protocolPattern.exec(rest);
+  let lowerProto;
   if (proto) {
     proto = proto[0];
-    var lowerProto = proto.toLowerCase();
+    lowerProto = proto.toLowerCase();
     this.protocol = lowerProto;
     rest = rest.slice(proto.length);
   }