diff --git a/lib/router.js b/lib/router.js
index d56a6ac..78b1c33 100644
--- a/lib/router.js
+++ b/lib/router.js
@@ -510,7 +510,7 @@ Router.prototype.register = function (path, methods, middleware, opts) {
     var added = false;
 
     if (!route.paramNames.length) {
-      var routeNestingLevel = route.path.split('/').length;
+      var routeNestingLevel = route.path.toString().split('/').length;
 
       added = stack.some(function (m, i) {
         var mNestingLevel = m.path.split('/').length;