diff --git a/modules/@angular/router/src/create_url_tree.ts b/modules/@angular/router/src/create_url_tree.ts
index e037a2e708..5825cacbce 100644
--- a/modules/@angular/router/src/create_url_tree.ts
+++ b/modules/@angular/router/src/create_url_tree.ts
@@ -199,7 +199,7 @@ function update(node: TreeNode<UrlSegment>| null, commands: any[]): TreeNode<Url
 
 function stringify(params: {[key: string]: any}): {[key: string]: string} {
   const res = {};
-  forEach(params, (v, k) => res[k] = v.toString());
+  forEach(params, (v, k) => res[k] = `${v}`);
   return res;
 }