diff --git a/index.polyfilled.js b/index.polyfilled.js
index 927e0e1e..00f92a59 100644
--- a/index.polyfilled.js
+++ b/index.polyfilled.js
@@ -1,4 +1,6 @@
 import {Router, Resolver} from './index.js';
+import * as pathToRegexp from 'path-to-regexp';
+Resolver.pathToRegexp = pathToRegexp;
 
 let isUrlAvailable, urlDocument, urlBase, urlAnchor;
 
diff --git a/src/resolver/generateUrls.js b/src/resolver/generateUrls.js
index bd3842c0..0c8b7195 100644
--- a/src/resolver/generateUrls.js
+++ b/src/resolver/generateUrls.js
@@ -7,10 +7,10 @@
  * LICENSE.txt file in the root directory of this source tree.
  */
 
+import {parse, tokensToFunction} from 'path-to-regexp';
 import Resolver from './resolver.js';
 import {isString} from '../utils.js';
 
-const {pathToRegexp} = Resolver;
 const cache = new Map();
 
 function cacheRoutes(routesByName, route, routes) {
@@ -49,7 +49,9 @@ function getRoutePath(route) {
   return path !== undefined ? path : '';
 }
 
-function generateUrls(router, options = {}) {
+function generateUrls(router, options = {
+  encode: encodeURIComponent
+}) {
   if (!(router instanceof Resolver)) {
     throw new TypeError('An instance of Resolver is expected');
   }
@@ -68,8 +70,8 @@ function generateUrls(router, options = {}) {
       }
     }
 
-    let regexp = cache.get(route.fullPath);
-    if (!regexp) {
+    let cached = cache.get(route.fullPath);
+    if (!cached) {
       let fullPath = getRoutePath(route);
       let rt = route.parent;
       while (rt) {
@@ -79,27 +81,27 @@ function generateUrls(router, options = {}) {
         }
         rt = rt.parent;
       }
-      const tokens = pathToRegexp.parse(fullPath);
-      const toPath = pathToRegexp.tokensToFunction(tokens);
+      const tokens = parse(fullPath);
       const keys = Object.create(null);
       for (let i = 0; i < tokens.length; i++) {
         if (!isString(tokens[i])) {
           keys[tokens[i].name] = true;
         }
       }
-      regexp = {toPath, keys};
-      cache.set(fullPath, regexp);
+      cached = {tokens, keys};
+      cache.set(fullPath, cached);
       route.fullPath = fullPath;
     }
 
-    let url = regexp.toPath(params, options) || '/';
+    const toPath = tokensToFunction(cached.tokens, options);
+    let url = toPath(params) || '/';
 
     if (options.stringifyQueryParams && params) {
       const queryParams = {};
       const keys = Object.keys(params);
       for (let i = 0; i < keys.length; i++) {
         const key = keys[i];
-        if (!regexp.keys[key]) {
+        if (!cached.keys[key]) {
           queryParams[key] = params[key];
         }
       }
diff --git a/src/resolver/matchPath.js b/src/resolver/matchPath.js
index 9feb1455..af38b34d 100644
--- a/src/resolver/matchPath.js
+++ b/src/resolver/matchPath.js
@@ -54,8 +54,10 @@ function matchPath(routepath, path, exact, parentKeys, parentParams) {
     const prop = key.name;
     const value = m[i];
     if (value !== undefined || !hasOwnProperty.call(params, prop)) {
-      if (key.repeat) {
-        params[prop] = value ? value.split(key.delimiter).map(decodeParam) : [];
+      if (key.modifier === '+' || key.modifier === '*') {
+        // by default, as of path-to-regexp 6.0.0, the default delimiters
+        // are `/`, `#` and `?`.
+        params[prop] = value ? value.split(/[/?#]/).map(decodeParam) : [];
       } else {
         params[prop] = value ? decodeParam(value) : value;
       }
diff --git a/src/resolver/resolver.js b/src/resolver/resolver.js
index 056cc445..15fbc1ee 100644
--- a/src/resolver/resolver.js
+++ b/src/resolver/resolver.js
@@ -7,7 +7,6 @@
  * LICENSE.txt file in the root directory of this source tree.
  */
 
-import {pathToRegexp} from 'path-to-regexp';
 import matchRoute from './matchRoute.js';
 import resolveRoute from './resolveRoute.js';
 import {toArray, ensureRoutes, isString, getNotFoundError, notFoundResult} from '../utils.js';
@@ -249,6 +248,4 @@ class Resolver {
   }
 }
 
-Resolver.pathToRegexp = pathToRegexp;
-
 export default Resolver;
diff --git a/src/router.js b/src/router.js
index d079598b..9455aab4 100644
--- a/src/router.js
+++ b/src/router.js
@@ -1,3 +1,4 @@
+import {compile} from 'path-to-regexp';
 import Resolver from './resolver/resolver.js';
 import generateUrls from './resolver/generateUrls.js';
 import setNavigationTriggers from './triggers/setNavigationTriggers.js';
@@ -39,7 +40,7 @@ function createLocation({pathname = '', search = '', hash = '', chain = [], para
     params,
     redirectFrom,
     getUrl: (userParams = {}) => getPathnameForRouter(
-      Router.pathToRegexp.compile(
+      compile(
         getMatchedPath(routes)
       )(Object.assign({}, params, userParams)),
       resolver
@@ -979,7 +980,7 @@ export class Router extends Resolver {
    */
   urlForPath(path, params) {
     return getPathnameForRouter(
-      Router.pathToRegexp.compile(path)(params),
+      compile(path)(params),
       this
     );
   }
diff --git a/test/.eslintrc.json b/test/.eslintrc.json
index fb4871f3..135b91b1 100644
--- a/test/.eslintrc.json
+++ b/test/.eslintrc.json
@@ -8,6 +8,7 @@
     "afterEach": false,
     "fixture": false,
     "it": false,
+    "xit": false,
     "expect": false,
     "gemini": false,
     "sinon": false,
diff --git a/test/router/router.spec.html b/test/router/router.spec.html
index f485ce3e..6b2ff4f7 100644
--- a/test/router/router.spec.html
+++ b/test/router/router.spec.html
@@ -796,7 +796,8 @@
               await router.ready;
             });
 
-            it('should invoke pathToRegexp', async() => {
+            // cannot mock the call to `compile()` from the 'pathToRegexp' package
+            xit('should invoke pathToRegexp', async() => {
               router.setRoutes([
                 {path: '/a/:id', component: 'x-a'}
               ]);
diff --git a/test/router/url-for.spec.html b/test/router/url-for.spec.html
index 768825b8..11a0d405 100644
--- a/test/router/url-for.spec.html
+++ b/test/router/url-for.spec.html
@@ -199,7 +199,8 @@
           expect(router.urlForName('without-slash')).to.equal('/base/bar');
         });
 
-        it('should use pathToRegexp', () => {
+        // cannot mock the call to `parse()` from the 'pathToRegexp' package
+        xit('should use pathToRegexp', () => {
           const parse = sinon.spy(Vaadin.Router.pathToRegexp, 'parse');
 
           try {
@@ -256,7 +257,8 @@
           expect(router.urlForPath('/bar')).to.equal('/base/bar');
         });
 
-        it('should use pathToRegexp', () => {
+        // cannot mock the call to `compile()` from the 'pathToRegexp' package
+        xit('should use pathToRegexp', () => {
           const compiledRegExp = sinon.stub().returns('/ok/url');
           const compile = sinon.stub(Vaadin.Router.pathToRegexp, 'compile').returns(compiledRegExp);