diff --git a/src/Migration/MailerTransportMigration.php b/src/Migration/MailerTransportMigration.php
index 786b29d..be5efd4 100644
--- a/src/Migration/MailerTransportMigration.php
+++ b/src/Migration/MailerTransportMigration.php
@@ -33,6 +33,7 @@ public function shouldRun(): bool
 
     public function run(): MigrationResult
     {
+        $this->connection->executeStatement("ALTER TABLE tl_nc_gateway CHANGE mailerTransport mailerTransport varchar(64) DEFAULT NULL");
         $this->connection->executeStatement("UPDATE tl_nc_gateway SET mailerTransport = NULL WHERE mailerTransport = ''");
 
         return $this->createResult(true);