diff --git a/README.md b/README.md
index 40cead91..b818d551 100644
--- a/README.md
+++ b/README.md
@@ -245,6 +245,19 @@ isEqual('/foo bar', '/foo%20bar', { encoding: true })
 // false
 ```
 
+### `withFragment`
+
+Add a fragment (or hash) to a URL:
+
+```ts
+withFragment('/foo', 'bar')
+// /foo#bar
+withFragment('/foo#bar', 'baz')
+// /foo#baz
+withFragment('/foo#bar', '')
+// /foo
+```
+
 ## License
 
 [MIT](./LICENSE)
diff --git a/src/utils.ts b/src/utils.ts
index 8fa951bf..dc074f6d 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -256,3 +256,9 @@ export function isEqual(a: string, b: string, options: CompareURLOptions = {}) {
   }
   return a === b;
 }
+
+export function withFragment(input: string, hash: string): string {
+  const parsed = parseURL(input);
+  parsed.hash = hash === "" ? "" : "#" + encodeURI(hash);
+  return stringifyParsedURL(parsed);
+}
diff --git a/test/utilities.test.ts b/test/utilities.test.ts
index 81240089..ba9a3af0 100644
--- a/test/utilities.test.ts
+++ b/test/utilities.test.ts
@@ -10,6 +10,7 @@ import {
   withoutProtocol,
   withProtocol,
   isScriptProtocol,
+  withFragment,
 } from "../src";
 
 describe("hasProtocol", () => {
@@ -256,3 +257,50 @@ describe("isEqual", () => {
     });
   }
 });
+
+describe("withFragment", () => {
+  const tests = [
+    {
+      input: "https://example.com",
+      fragment: "foo",
+      out: "https://example.com#foo",
+    },
+    {
+      input: "https://example.com#bar",
+      fragment: "foo",
+      out: "https://example.com#foo",
+    },
+    { input: "https://example.com", fragment: "", out: "https://example.com" },
+    {
+      input: "https://example.com#bar",
+      fragment: "",
+      out: "https://example.com",
+    },
+    {
+      input: "https://example.com#bar",
+      fragment: "0",
+      out: "https://example.com#0",
+    },
+    {
+      input: "https://example.com#bar",
+      fragment: "foo bar",
+      out: "https://example.com#foo%20bar",
+    },
+    {
+      input: "https://example.com#bar",
+      fragment: "foo/bar",
+      out: "https://example.com#foo/bar",
+    },
+    {
+      input: "https://example.com?foo=bar",
+      fragment: "baz",
+      out: "https://example.com?foo=bar#baz",
+    },
+  ];
+
+  for (const t of tests) {
+    test(`${t.input} + ${t.fragment}`, () => {
+      expect(withFragment(t.input, t.fragment)).toBe(t.out);
+    });
+  }
+});