diff --git a/core/Migrations/Version21000Date20201120141228.php b/core/Migrations/Version21000Date20201120141228.php
index 7f3eda2309bad..bc15801774346 100644
--- a/core/Migrations/Version21000Date20201120141228.php
+++ b/core/Migrations/Version21000Date20201120141228.php
@@ -63,6 +63,8 @@ public function changeSchema(IOutput $output, Closure $schemaClosure, array $opt
 		if ($schema->hasTable('systemtag')) {
 			$table = $schema->getTable('systemtag');
 			if ($table->hasColumn('assignable')) {
+				$table->dropIndex('tag_ident');
+				$table->addUniqueIndex(['name', 'visibility', 'editable'], 'tag_ident');
 				$table->dropColumn('assignable');
 			}
 		}