diff --git a/keyserver/src/database/migration-config.js b/keyserver/src/database/migration-config.js
--- a/keyserver/src/database/migration-config.js
+++ b/keyserver/src/database/migration-config.js
@@ -74,6 +74,23 @@
       );
     },
   ],
+  [
+    9,
+    async () => {
+      await dbQuery(
+        SQL`
+          ALTER TABLE messages
+            ADD COLUMN IF NOT EXISTS target_message bigint(20) DEFAULT NULL;
+        `,
+      );
+      await dbQuery(
+        SQL`
+          ALTER TABLE messages
+            ADD INDEX target_message (target_message);
+        `,
+      );
+    },
+  ],
 ]);
 const newDatabaseVersion: number = Math.max(...migrations.keys());
 
diff --git a/keyserver/src/database/setup-db.js b/keyserver/src/database/setup-db.js
--- a/keyserver/src/database/setup-db.js
+++ b/keyserver/src/database/setup-db.js
@@ -88,7 +88,8 @@
         type tinyint(3) UNSIGNED NOT NULL,
         content mediumtext COLLATE utf8mb4_bin,
         time bigint(20) NOT NULL,
-        creation varchar(255) COLLATE utf8mb4_bin DEFAULT NULL
+        creation varchar(255) COLLATE utf8mb4_bin DEFAULT NULL,
+        target_message bigint(20) DEFAULT NULL
       ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
 
       CREATE TABLE notifications (
@@ -263,7 +264,8 @@
       ALTER TABLE messages
         ADD PRIMARY KEY (id),
         ADD UNIQUE KEY user_creation (user,creation),
-        ADD KEY thread (thread);
+        ADD KEY thread (thread),
+        ADD INDEX target_message (target_message);
 
       ALTER TABLE notifications
         ADD PRIMARY KEY (id),