diff --git a/core/upgrade/upgrade.php b/core/upgrade/upgrade.php
index ae27681d1c..f70ad7f163 100644
--- a/core/upgrade/upgrade.php
+++ b/core/upgrade/upgrade.php
@@ -185,7 +185,7 @@
 		if (isset($argv[2]) && $argv[2] == 'data_types') {
 			$obj->data_types = true;
 		}
-		echo $obj->schema($format);
+		echo $obj->schema($format ?? '');
 	}
 
 //restore the default menu