diff --git a/packages/netlify-cms-backend-bitbucket/src/AuthenticationPage.js b/packages/netlify-cms-backend-bitbucket/src/AuthenticationPage.js
index 3f7fd729..151b1e53 100644
--- a/packages/netlify-cms-backend-bitbucket/src/AuthenticationPage.js
+++ b/packages/netlify-cms-backend-bitbucket/src/AuthenticationPage.js
@@ -26,7 +26,7 @@ export default class BitbucketAuthenticationPage extends React.Component {
       site_id:
         document.location.host.split(':')[0] === 'localhost'
           ? 'cms.netlify.com'
-          : this.props.site_id,
+          : this.props.siteId,
       auth_endpoint: this.props.authEndpoint,
     };
     const auth = new NetlifyAuthenticator(cfg);