diff --git a/src/Upgrades/Upgrade28.php b/src/Upgrades/Upgrade28.php
new file mode 100644
index 00000000..a2eb9bef
--- /dev/null
+++ b/src/Upgrades/Upgrade28.php
@@ -0,0 +1,12 @@
+<?php
+namespace Szurubooru\Upgrades;
+use Szurubooru\DatabaseConnection;
+
+class Upgrade28 implements IUpgrade
+{
+	public function run(DatabaseConnection $databaseConnection)
+	{
+		$pdo = $databaseConnection->getPDO();
+		$pdo->exec('CREATE INDEX idx_comments_postId ON comments(postId)');
+	}
+}
diff --git a/src/di.php b/src/di.php
index 1b6b3dae..bd4145cd 100644
--- a/src/di.php
+++ b/src/di.php
@@ -43,6 +43,7 @@ return [
 			$container->get(\Szurubooru\Upgrades\Upgrade25::class),
 			$container->get(\Szurubooru\Upgrades\Upgrade26::class),
 			$container->get(\Szurubooru\Upgrades\Upgrade27::class),
+			$container->get(\Szurubooru\Upgrades\Upgrade28::class),
 		];
 	}),