diff --git a/ts/test-both/util/getProvisioningUrl_test.ts b/ts/test-both/util/getProvisioningUrl_test.ts
new file mode 100644
index 000000000000..6c415ff659ca
--- /dev/null
+++ b/ts/test-both/util/getProvisioningUrl_test.ts
@@ -0,0 +1,23 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+import { size } from '../../util/iterables';
+
+import { getProvisioningUrl } from '../../util/getProvisioningUrl';
+
+describe('getProvisioningUrl', () => {
+  it('returns a URL with a UUID and public key', () => {
+    const uuid = 'a08bf1fd-1799-427f-a551-70af747e3956';
+    const publicKey = new Uint8Array([9, 8, 7, 6, 5, 4, 3]);
+
+    const result = getProvisioningUrl(uuid, publicKey);
+    const resultUrl = new URL(result);
+
+    assert(result.startsWith('tsdevice:/?'));
+    assert.strictEqual(resultUrl.protocol, 'tsdevice:');
+    assert.strictEqual(size(resultUrl.searchParams.entries()), 2);
+    assert.strictEqual(resultUrl.searchParams.get('uuid'), uuid);
+    assert.strictEqual(resultUrl.searchParams.get('pub_key'), 'CQgHBgUEAw==');
+  });
+});
diff --git a/ts/textsecure/AccountManager.ts b/ts/textsecure/AccountManager.ts
index b859f3aa1116..c4d6cf5a6f75 100644
--- a/ts/textsecure/AccountManager.ts
+++ b/ts/textsecure/AccountManager.ts
@@ -1,4 +1,4 @@
-// Copyright 2020 Signal Messenger, LLC
+// Copyright 2020-2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 /* eslint-disable @typescript-eslint/no-explicit-any */
@@ -29,6 +29,7 @@ import {
 } from '../Curve';
 import { isMoreRecentThan, isOlderThan } from '../util/timestamp';
 import { ourProfileKeyService } from '../services/ourProfileKey';
+import { getProvisioningUrl } from '../util/getProvisioningUrl';
 
 const ARCHIVE_AGE = 30 * 24 * 60 * 60 * 1000;
 const PREKEY_ROTATION_AGE = 24 * 60 * 60 * 1000;
@@ -222,12 +223,11 @@ export default class AccountManager extends EventTarget {
                 const proto = window.textsecure.protobuf.ProvisioningUuid.decode(
                   request.body
                 );
-                const url = [
-                  'tsdevice:/?uuid=',
-                  proto.uuid,
-                  '&pub_key=',
-                  encodeURIComponent(btoa(utils.getString(pubKey))),
-                ].join('');
+                const { uuid } = proto;
+                if (!uuid) {
+                  throw new Error('registerSecondDevice: expected a UUID');
+                }
+                const url = getProvisioningUrl(uuid, pubKey);
 
                 if (window.CI) {
                   window.CI.setProvisioningURL(url);
diff --git a/ts/util/getProvisioningUrl.ts b/ts/util/getProvisioningUrl.ts
new file mode 100644
index 000000000000..ce143b511570
--- /dev/null
+++ b/ts/util/getProvisioningUrl.ts
@@ -0,0 +1,15 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { arrayBufferToBase64 } from '../Crypto';
+
+export function getProvisioningUrl(
+  uuid: string,
+  publicKey: ArrayBuffer
+): string {
+  const params = new URLSearchParams({
+    uuid,
+    pub_key: arrayBufferToBase64(publicKey),
+  });
+  return `tsdevice:/?${params.toString()}`;
+}