diff --git a/modules/@angular/router/src/create_url_tree.ts b/modules/@angular/router/src/create_url_tree.ts
index 1030409047..2c0ad768af 100644
--- a/modules/@angular/router/src/create_url_tree.ts
+++ b/modules/@angular/router/src/create_url_tree.ts
@@ -124,7 +124,7 @@ function findStartingPosition(
 }
 
 function getPath(command: any): any {
-  if (!(typeof command === 'string')) return command;
+  if (!(typeof command === 'string')) return command.toString();
   const parts = command.toString().split(':');
   return parts.length > 1 ? parts[1] : command;
 }
@@ -202,6 +202,7 @@ function createNewSegment(segment: UrlSegment, startIndex: number, commands: any
   const paths = segment.pathsWithParams.slice(0, startIndex);
   let i = 0;
   while (i < commands.length) {
+    // if we start with an object literal, we need to reuse the path part from the segment
     if (i === 0 && (typeof commands[0] === 'object')) {
       const p = segment.pathsWithParams[startIndex];
       paths.push(new UrlPathWithParams(p.path, commands[0]));
diff --git a/modules/@angular/router/test/create_url_tree.spec.ts b/modules/@angular/router/test/create_url_tree.spec.ts
index 5a602fe9e8..c810b7b699 100644
--- a/modules/@angular/router/test/create_url_tree.spec.ts
+++ b/modules/@angular/router/test/create_url_tree.spec.ts
@@ -20,6 +20,15 @@ describe('createUrlTree', () => {
     expect(serializer.serialize(t)).toEqual("/one/11/two/22");
   });
 
+  
+  it("should stringify positional parameters", () => {
+    const p = serializer.parse("/a/b");
+    const t = createRoot(p, ["/one", 11]);
+    const params = t.root.children[PRIMARY_OUTLET].pathsWithParams;
+    expect(params[0].path).toEqual("one");
+    expect(params[1].path).toEqual("11");
+  });
+
   it("should preserve secondary segments", () => {
     const p = serializer.parse("/a/11/b(right:c)");
     const t = createRoot(p, ["/a", 11, 'd']);