diff --git a/src/client.ts b/src/client.ts
index ad23a28..4f64feb 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -89,7 +89,7 @@ export async function register(options: RegisterOptions): Promise<RegistrationJS
         authenticatorSelection: {
             userVerification: options.userVerification,
             authenticatorAttachment: getAuthAttachment(options.hints),
-            residentKey: options.discoverable,
+            residentKey: options.discoverable ?? 'preferred', // see https://developer.mozilla.org/en-US/docs/Web/API/PublicKeyCredentialCreationOptions#residentkey
             requireResidentKey: (options.discoverable === 'required') // mainly for backwards compatibility, see https://www.w3.org/TR/webauthn/#dictionary-authenticatorSelection
         },
         attestation: "direct"