diff --git a/cli/tests/unit/urlpattern_test.ts b/cli/tests/unit/urlpattern_test.ts
index 9bed092355..cb5fc76c53 100644
--- a/cli/tests/unit/urlpattern_test.ts
+++ b/cli/tests/unit/urlpattern_test.ts
@@ -1,5 +1,6 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 import { assert, assertEquals } from "./test_util.ts";
+import { assertType, IsExact } from "../../../test_util/std/testing/types.ts";
 
 Deno.test(function urlPatternFromString() {
   const pattern = new URLPattern("https://deno.land/foo/:bar");
@@ -13,6 +14,10 @@ Deno.test(function urlPatternFromString() {
   assert(match);
   assertEquals(match.pathname.input, "/foo/x");
   assertEquals(match.pathname.groups, { bar: "x" });
+
+  // group values should be nullable
+  const val = match.pathname.groups.val;
+  assertType<IsExact<typeof val, string | undefined>>(true);
 });
 
 Deno.test(function urlPatternFromStringWithBase() {
diff --git a/cli/tsc/dts/lib.dom.extras.d.ts b/cli/tsc/dts/lib.dom.extras.d.ts
index 2c593b2cbe..9116596a6a 100644
--- a/cli/tsc/dts/lib.dom.extras.d.ts
+++ b/cli/tsc/dts/lib.dom.extras.d.ts
@@ -23,7 +23,7 @@ declare type URLPatternInput = string | URLPatternInit;
 
 declare interface URLPatternComponentResult {
   input: string;
-  groups: Record<string, string>;
+  groups: Record<string, string | undefined>;
 }
 
 /** `URLPatternResult` is the object returned from `URLPattern.exec`. */
diff --git a/ext/url/lib.deno_url.d.ts b/ext/url/lib.deno_url.d.ts
index 1d5f840199..9a8c155d99 100644
--- a/ext/url/lib.deno_url.d.ts
+++ b/ext/url/lib.deno_url.d.ts
@@ -206,7 +206,7 @@ declare type URLPatternInput = string | URLPatternInit;
 /** @category Web APIs */
 declare interface URLPatternComponentResult {
   input: string;
-  groups: Record<string, string>;
+  groups: Record<string, string | undefined>;
 }
 
 /** `URLPatternResult` is the object returned from `URLPattern.exec`.