diff --git a/src/Tests/MigrateUpgradeTestBase.php b/src/Tests/MigrateUpgradeTestBase.php
index b612ecf..2f25363 100644
--- a/src/Tests/MigrateUpgradeTestBase.php
+++ b/src/Tests/MigrateUpgradeTestBase.php
@@ -103,7 +103,7 @@ abstract class MigrateUpgradeTestBase extends WebTestBase {
       $prefix = is_array($connection_info['prefix']) ? $connection_info['prefix']['default'] : $connection_info['prefix'];
       // Simpletest uses 7 character prefixes at most so this can't cause
       // collisions.
-      $connection_info['prefix'] = $prefix . 'M';
+      $connection_info['prefix'] = $prefix . '0';
     }
 
     Database::addConnectionInfo('migrate_upgrade', 'default', $connection_info);