diff --git a/src/applications/auth/provider/PhabricatorAuthProviderLDAP.php b/src/applications/auth/provider/PhabricatorAuthProviderLDAP.php
index fb69da7a97..1c9844a34f 100644
--- a/src/applications/auth/provider/PhabricatorAuthProviderLDAP.php
+++ b/src/applications/auth/provider/PhabricatorAuthProviderLDAP.php
@@ -150,25 +150,27 @@ final class PhabricatorAuthProviderLDAP
       return array($account, $response);
     }
 
-    try {
-      if (strlen($username) && $has_password) {
-        $adapter = $this->getAdapter();
-        $adapter->setLoginUsername($username);
-        $adapter->setLoginPassword($password);
+    if ($request->isFormPost()) {
+      try {
+        if (strlen($username) && $has_password) {
+          $adapter = $this->getAdapter();
+          $adapter->setLoginUsername($username);
+          $adapter->setLoginPassword($password);
 
-        // TODO: This calls ldap_bind() eventually, which dumps cleartext
-        // passwords to the error log. See note in PhutilAuthAdapterLDAP.
-        // See T3351.
+          // TODO: This calls ldap_bind() eventually, which dumps cleartext
+          // passwords to the error log. See note in PhutilAuthAdapterLDAP.
+          // See T3351.
 
-        DarkConsoleErrorLogPluginAPI::enableDiscardMode();
-          $account_id = $adapter->getAccountID();
-        DarkConsoleErrorLogPluginAPI::disableDiscardMode();
-      } else {
-        throw new Exception("Username and password are required!");
+          DarkConsoleErrorLogPluginAPI::enableDiscardMode();
+            $account_id = $adapter->getAccountID();
+          DarkConsoleErrorLogPluginAPI::disableDiscardMode();
+        } else {
+          throw new Exception("Username and password are required!");
+        }
+      } catch (Exception $ex) {
+        // TODO: Make this cleaner.
+        throw $ex;
       }
-    } catch (Exception $ex) {
-      // TODO: Make this cleaner.
-      throw $ex;
     }
 
     return array($this->loadOrCreateAccount($account_id), $response);
diff --git a/src/applications/auth/provider/PhabricatorAuthProviderPassword.php b/src/applications/auth/provider/PhabricatorAuthProviderPassword.php
index 7b93fde350..a779df0f2d 100644
--- a/src/applications/auth/provider/PhabricatorAuthProviderPassword.php
+++ b/src/applications/auth/provider/PhabricatorAuthProviderPassword.php
@@ -163,22 +163,25 @@ final class PhabricatorAuthProviderPassword
     $account = null;
     $log_user = null;
 
-    if (!$require_captcha || $captcha_valid) {
-      $username_or_email = $request->getStr('username');
-      if (strlen($username_or_email)) {
-        $user = id(new PhabricatorUser())->loadOneWhere(
-          'username = %s',
-          $username_or_email);
+    if ($request->isFormPost()) {
+      if (!$require_captcha || $captcha_valid) {
+        $username_or_email = $request->getStr('username');
+        if (strlen($username_or_email)) {
+          $user = id(new PhabricatorUser())->loadOneWhere(
+            'username = %s',
+            $username_or_email);
 
-        if (!$user) {
-          $user = PhabricatorUser::loadOneWithEmailAddress($username_or_email);
-        }
+          if (!$user) {
+            $user = PhabricatorUser::loadOneWithEmailAddress(
+              $username_or_email);
+          }
 
-        if ($user) {
-          $envelope = new PhutilOpaqueEnvelope($request->getStr('password'));
-          if ($user->comparePassword($envelope)) {
-            $account = $this->loadOrCreateAccount($user->getPHID());
-            $log_user = $user;
+          if ($user) {
+            $envelope = new PhutilOpaqueEnvelope($request->getStr('password'));
+            if ($user->comparePassword($envelope)) {
+              $account = $this->loadOrCreateAccount($user->getPHID());
+              $log_user = $user;
+            }
           }
         }
       }