diff --git a/src/applications/auth/controller/PhabricatorAuthLoginController.php b/src/applications/auth/controller/PhabricatorAuthLoginController.php
--- a/src/applications/auth/controller/PhabricatorAuthLoginController.php
+++ b/src/applications/auth/controller/PhabricatorAuthLoginController.php
@@ -35,6 +35,7 @@
       return $response;
     }
 
+    $invite = $this->loadInvite();
     $provider = $this->provider;
 
     try {
@@ -103,7 +104,7 @@
       // The account is not yet attached to a Phabricator user, so this is
       // either a registration or an account link request.
       if (!$viewer->isLoggedIn()) {
-        if ($provider->shouldAllowRegistration()) {
+        if ($provider->shouldAllowRegistration() || $invite) {
           return $this->processRegisterUser($account);
         } else {
           return $this->renderError(
diff --git a/src/applications/auth/controller/PhabricatorAuthRegisterController.php b/src/applications/auth/controller/PhabricatorAuthRegisterController.php
--- a/src/applications/auth/controller/PhabricatorAuthRegisterController.php
+++ b/src/applications/auth/controller/PhabricatorAuthRegisterController.php
@@ -11,10 +11,12 @@
     $viewer = $this->getViewer();
     $account_key = $request->getURIData('akey');
 
-    if ($request->getUser()->isLoggedIn()) {
+    if ($viewer->isLoggedIn()) {
       return id(new AphrontRedirectResponse())->setURI('/');
     }
 
+    $invite = $this->loadInvite();
+
     $is_setup = false;
     if (strlen($account_key)) {
       $result = $this->loadAccountForRegistrationOrLinking($account_key);
@@ -27,7 +29,7 @@
       $is_default = true;
       $is_setup = true;
     } else {
-      list($account, $provider, $response) = $this->loadDefaultAccount();
+      list($account, $provider, $response) = $this->loadDefaultAccount($invite);
       $is_default = true;
     }
 
@@ -35,8 +37,6 @@
       return $response;
     }
 
-    $invite = $this->loadInvite();
-
     if (!$is_setup) {
       if (!$provider->shouldAllowRegistration()) {
         if ($invite) {
@@ -643,17 +643,20 @@
       ->appendChild($view);
   }
 
-  private function loadDefaultAccount() {
+  private function loadDefaultAccount($invite) {
     $providers = PhabricatorAuthProvider::getAllEnabledProviders();
     $account = null;
     $provider = null;
     $response = null;
 
     foreach ($providers as $key => $candidate_provider) {
-      if (!$candidate_provider->shouldAllowRegistration()) {
-        unset($providers[$key]);
-        continue;
+      if (!$invite) {
+        if (!$candidate_provider->shouldAllowRegistration()) {
+          unset($providers[$key]);
+          continue;
+        }
       }
+
       if (!$candidate_provider->isDefaultRegistrationProvider()) {
         unset($providers[$key]);
       }