diff --git a/index.src.html b/index.src.html
index 62bca63..d2c9423 100644
--- a/index.src.html
+++ b/index.src.html
@@ -365,8 +365,8 @@ <h1>Credential Management Level 1</h1>
   mechanism in the [=credential chooser=] by providing a friendly name and icon:
 
   <pre class="idl">
-    [NoInterfaceObject, SecureContext]
-    interface CredentialUserData {
+    [SecureContext]
+    interface mixin CredentialUserData {
       readonly attribute USVString name;
       readonly attribute USVString iconURL;
     };
@@ -1116,7 +1116,7 @@ <h4 id="algorithm-prevent-silent-access" algorithm>Prevent Silent Access</h4>
     interface PasswordCredential : Credential {
       readonly attribute USVString password;
     };
-    PasswordCredential implements CredentialUserData;
+    PasswordCredential includes CredentialUserData;
 
     partial dictionary CredentialRequestOptions {
       boolean password = false;
@@ -1444,7 +1444,7 @@ <h4 algorithm id="passwordcredential-matching">
       readonly attribute USVString provider;
       readonly attribute DOMString? protocol;
     };
-    FederatedCredential implements CredentialUserData;
+    FederatedCredential includes CredentialUserData;
 
     dictionary FederatedCredentialRequestOptions {
       sequence&lt;USVString&gt; providers;