diff --git a/src/ORM/RelatedData/StandardRelatedDataService.php b/src/ORM/RelatedData/StandardRelatedDataService.php
index 2c3eab624..04501fc23 100644
--- a/src/ORM/RelatedData/StandardRelatedDataService.php
+++ b/src/ORM/RelatedData/StandardRelatedDataService.php
@@ -162,7 +162,7 @@ class StandardRelatedDataService implements RelatedDataService
                 $tableName = $this->dataObjectSchema->tableName($candidateClass);
                 break;
             }
-            $candidateClass = get_parent_class($class ?? '');
+            $candidateClass = get_parent_class($candidateClass ?? '');
         }
         return $tableName;
     }
diff --git a/tests/php/Security/SecurityDefaultAdminTest.php b/tests/php/Security/SecurityDefaultAdminTest.php
index ec691936b..082e7895b 100644
--- a/tests/php/Security/SecurityDefaultAdminTest.php
+++ b/tests/php/Security/SecurityDefaultAdminTest.php
@@ -7,6 +7,7 @@ use SilverStripe\Security\Member;
 use SilverStripe\Security\PasswordEncryptor;
 use SilverStripe\Security\Permission;
 use SilverStripe\Security\DefaultAdminService;
+use SilverStripe\Security\Security;
 
 class SecurityDefaultAdminTest extends SapphireTest
 {
@@ -35,6 +36,7 @@ class SecurityDefaultAdminTest extends SapphireTest
             $this->defaultUsername = null;
             $this->defaultPassword = null;
         }
+        Security::config()->set('password_encryption_algorithm', 'blowfish');
         DefaultAdminService::setDefaultAdmin('admin', 'password');
         Permission::reset();
     }