diff --git a/src/Controller/ConfigController.php b/src/Controller/ConfigController.php
index aa6c250cb..fde92ddaa 100644
--- a/src/Controller/ConfigController.php
+++ b/src/Controller/ConfigController.php
@@ -312,7 +312,7 @@ class ConfigController extends AbstractController
 
         $user = $this->getUser();
 
-        $user->setGoogleAuthenticatorSecret(null);
+        $user->setGoogleAuthenticatorSecret('');
         $user->setGoogleAuthenticator(false);
         $user->setBackupCodes(null);
 
diff --git a/tests/Controller/ConfigControllerTest.php b/tests/Controller/ConfigControllerTest.php
index d0d557bc8..ae89203ad 100644
--- a/tests/Controller/ConfigControllerTest.php
+++ b/tests/Controller/ConfigControllerTest.php
@@ -1292,7 +1292,7 @@ class ConfigControllerTest extends WallabagTestCase
         $this->assertGreaterThan(0, \count($user->getBackupCodes()));
 
         // Restore user
-        $user->setGoogleAuthenticatorSecret(null);
+        $user->setGoogleAuthenticatorSecret('');
         $user->setGoogleAuthenticator(false);
         $user->setBackupCodes([]);
         $em->persist($user);
@@ -1328,7 +1328,7 @@ class ConfigControllerTest extends WallabagTestCase
             ->getRepository(User::class)
             ->findOneByUsername('admin');
 
-        $this->assertNull($user->getGoogleAuthenticatorSecret());
+        $this->assertEmpty($user->getGoogleAuthenticatorSecret());
         $this->assertEmpty($user->getBackupCodes());
         $this->assertFalse($user->isGoogleTwoFactor());
     }