diff --git a/lib/url.js b/lib/url.js
index b6b5376c379a6c..4ec0ad3ee11d79 100644
--- a/lib/url.js
+++ b/lib/url.js
@@ -958,7 +958,8 @@ Url.prototype.resolveObject = function resolveObject(relative) {
     srcPath.unshift('');
   }
 
-  if (hasTrailingSlash && (srcPath.join('/').substr(-1) !== '/')) {
+  const srcPathSlashes = srcPath.join('/');
+  if (hasTrailingSlash && (srcPathSlashes.substring(srcPathJoin.length - 1) !== '/')) {
     srcPath.push('');
   }
 
@@ -990,7 +991,7 @@ Url.prototype.resolveObject = function resolveObject(relative) {
     result.pathname = null;
     result.path = null;
   } else {
-    result.pathname = srcPath.join('/');
+    result.pathname = srcPathSlashes;
   }
 
   // To support request.http